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Sample records for allen belt protons

  1. Precipitation of relativistic electrons of the Van Allen belts into the proton aurora

    SciTech Connect

    Jordanova, Vania K; Miyoshi, Y; Sakaguchi, K; Shiokawa, K; Evans, D S; Connors, M

    2008-01-01

    The Van Allen electron belts consist of two regions encircling the earth in which relativistic electrons are trapped in the earth's magnetic field. Populations of relativistic electrons in the Van Allen belts vary greatly with geomagnetic disturbance and they are a major source of damage to space vehicles. In order to know when and by how much these populations of relativistic electrons increase, it is important to elucidate not only the cause of acceleration of relativistic electrons but also the cause of their loss from the Van Allen belts. Here we show the first evidence that left-hand polarized electromagnetic ion cyclotron (EMIC) plasma waves can cause the loss of relativistic electrons into the atmosphere, on the basis of results of an excellent set of ground and satellite observations showing coincident precipitation of ions with energies of tens of keV and of relativistic electrons into an isolated proton aurora. The proton aurora was produced by precipitation of ions with energies of tens of keV due to EMIC waves near the plasma pause, which is a manifestation of wave-particle interactions. These observations clarify that ions with energies of tens of keV affect the evolution of relativistic electrons in the Van Allen belts via parasitic resonance with EMIC waves, an effect that was first theoretically predicted in the early 1970's.

  2. Effect of the orbital debris environment on the high-energy Van Allen proton belt

    NASA Technical Reports Server (NTRS)

    Konradi, Andrei

    1988-01-01

    The lifetimes of high-energy (greater than 55 MeV) protons in the Van Allen radiation belt are calculated, assuming that in time the protons will collide with and be absorbed by particulate orbiting material. The calculations are based on the NASA/DoD Civil Needs Database for orbital debris (Gaines, 1966) and moderate assumptions of future space traffic. It is found that the lifetimes of high-energy protons below 1500 km will decrease, leading to a noticeable redution in their fluxes.

  3. Innermost Van Allen Radiation Belt for High Energy Protons at Saturn

    NASA Technical Reports Server (NTRS)

    Cooper, John F.

    2008-01-01

    The high energy proton radiation belts of Saturn are energetically dominated by the source from cosmic ray albedo neutron decay (CRAND), trapping of protons from beta decay of neutrons emitted from galactic cosmic ray nuclear interactions with the main rings. These belts were originally discovered in wide gaps between the A-ring, Janus/Epimetheus, Mimas, and Enceladus. The narrow F and G rings significant affected the CRAND protons but did not produce total depletion. Voyager 2 measurements subsequently revealed an outermost CRAND proton belt beyond Enceladus. Although the source rate is small, the trapping times limited by radial magnetospheric diffusion are very long, about ten years at peak measured flux inwards of the G ring, so large fluxes can accumulate unless otherwise limited in the trapping region by neutral gas, dust, and ring body interactions. One proposed final extension of the Cassini Orbiter mission would place perikrone in a 3000-km gap between the inner D ring and the upper atmosphere of Saturn. Experience with CRAND in the Earth's inner Van Allen proton belt suggests that a similar innermost belt might be found in this comparably wide region at Saturn. Radial dependence of magnetospheric diffusion, proximity to the ring neutron source, and northward magnetic offset of Saturn's magnetic equator from the ring plane could potentially produce peak fluxes several orders of magnitude higher than previously measured outside the main rings. Even brief passes through such an intense environment of highly penetrating protons would be a significant concern for spacecraft operations and science observations. Actual fluxes are limited by losses in Saturn's exospheric gas and in a dust environment likely comparable to that of the known CRAND proton belts. The first numerical model of this unexplored radiation belt is presented to determine limits on peak magnitude and radial profile of the proton flux distribution.

  4. Remarkable new results for high-energy protons and electrons in the inner Van Allen belt regions

    NASA Astrophysics Data System (ADS)

    Baker, Daniel N.

    2016-04-01

    Early observations indicated that the Earth's Van Allen radiation belts could be separated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. Subsequent studies showed that electrons of moderate energy (less than about one megaelectronvolt) often populate both zones, with a deep 'slot' region largely devoid of particles between them. The two-belt radiation structure was explained as arising from strong electron interactions with plasmaspheric hiss just inside the plasmapause boundary with the inner edge of the outer radiation zone corresponding to the minimum plasmapause location.. Recent Van Allen Probes observations have revealed an unexpected radiation belt morphology, especially at ultrarelativistic kinetic energies (more than several megaelectronvolts). The data show an exceedingly sharp inner boundary for the ultrarelativistic electrons right at L=2.8. Additional, concurrently measured data reveal that this barrier to inward electron radial transport is likely due to scattering by powerful human electromagnetic transmitter (VLF) wave fields. We show that weak, but persistent, wave-particle pitch angle scattering deep inside the Earth's plasmasphere due to manmade signals can act to create an almost impenetrable barrier through which the most energetic Van Allen belt electrons cannot migrate. Inside of this distance, the Van Allen Probes data show that high energy (20 -100 MeV) protons have a double belt structure with a stable peak of flux at L~1.5 and a much more variable belt peaking at L~2.3.

  5. Effect of the orbital debris environment on the high-energy van allen proton belt.

    PubMed

    Konradi, A

    1988-12-02

    Orbital debris in the near-Earth environment has reached a number density sufficient for a significant collisional interaction with some of the long-lived high-energy protons in the radiation belt. As a result of a continuing buildup of a shell of man-made debris, the lifetimes of high-energy protons whose trajectories remain below 1500 kilometers will decrease to the point where in the next decades we can expect a noticeable reduction in their fluxes.

  6. Comparison of Van Allen Probes radiation belt proton data with test particle simulation for the 17 March 2015 storm

    NASA Astrophysics Data System (ADS)

    Engel, M. A.; Kress, B. T.; Hudson, M. K.; Selesnick, R. S.

    2016-11-01

    The loss of protons in the outer part of the inner radiation belt (L = 2 to 3) during the 17 March 2015 geomagnetic storm was investigated using test particle simulations that follow full Lorentz trajectories with both magnetic and electric fields calculated from an empirical model. The simulation results presented here are compared with proton pitch angle measurements from the Van Allen Probe satellites Relativistic Electron Proton Telescope (REPT) instrument before and after the coronal mass ejection-shock-driven storm of 17-18 March 2015, with minimum Dst =- 223 nT, the strongest storm of Solar Cycle 24, for four different energy ranges with 30, 38, 50, and 66 MeV mean energies. Two simulations have been run, one with an inductive electric field and one without. All four energy channels show good agreement with the Van Allen Probes REPT measurements for low L (L < 2.4) in both simulations but diverge for higher L values. The inclusion of the inductive electric field, calculated from the time-changing magnetic field, significantly improves the agreement between simulation and REPT measurements at L > 2.4. A previous study using the Highly Elliptical Orbiter 3 spacecraft also showed improved agreement when including the inductive electric field but was unable to compare effects on the pitch angle distributions.

  7. New Results About the Earth’s Van Allen Radiation Belts

    NASA Astrophysics Data System (ADS)

    Baker, Daniel

    2015-01-01

    The first great scientific discovery of the Space Age was that the Earth is enshrouded in toroids, or 'belts', of very high-energy magnetically trapped charged particles. Early observations of the radiation environment clearly indicated that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. Subsequent studies showed that electrons in the energy range 100 keV < E< 1 MeV often populated both the inner and outer zones with a pronounced 'slot' region relatively devoid of energetic electrons existing between them. This two-belt structure for the Van Allen moderate-energy electron component was explained as being due to strong interactions of electrons with electromagnetic waves just inside the cold plasma (plasmapause) boundary. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions. However, recent observations by the NASA dual-spacecraft Van Allen Probes mission have revealed wholly unexpected properties of the radiation belts, especially at highly relativistic (E > 2 MeV) and ultra-relativistic (E > 5 MeV) kinetic energies. In this presentation we show using high spatial and temporal resolution data from the Relativistic Electron-Proton Telescope (REPT) experiment on board the Van Allen Probes that multiple belts can exist concurrently and that an exceedingly sharp inner boundary exists for ultra-relativistic electrons. Using additionally available Van Allen Probes data, we demonstrate that these remarkable features of energetic electrons are not due to a physical boundary within Earth's intrinsic magnetic field. Neither is it likely that human-generated electromagnetic transmitter wave fields might produce such effects. Rather, we conclude from these unique measurements that slow natural inward radial diffusion combined with weak, but persistent, wave-particle pitch angle

  8. Radition belt dynamics : Recent results from van Allen Probes and future observations from CeREs

    NASA Astrophysics Data System (ADS)

    Kanekal, Shrikanth; O'Brien, Paul; Baker, Daniel N.; Ogasawara, Keiichi; Fennell, Joseph; Christian, Eric; Claudepierre, Seth; Livi, Stefano; Desai, Mihir; Li, Xinlin; Jaynes, Allison; Turner, Drew; Jones, Ashley; Schiller, Quintin

    2016-07-01

    We describe recent observations of the Earth's radiation belts made by instruments on board the Van Allen Probes mission, particularly the Relativistic Electron Proton Telescope (REPT) and the Magnetic Electron Ion spectrometer (MagEIS). These observations have significantly advanced our understanding of terrestrial radiation belt dynamics. The Van Allen Probes mission comprises two identically instrumented spacecraft which were launched 31 August, 2012 into low-inclination lapping equatorial orbits. The orbit periods are about 9 hours, with perigees and apogees of of ~600 km and 5.8 RE respectively. We discuss the new scientific findings of the Van Allen Probes mission regarding the physics of energization and loss of relativistic electrons and their implications for future low-cost missions, especially CubeSats. We describe the CeREs (a Compact Radiation belt Explorer) CubeSat mission currently being built at the Goddard Space Flight Center, and carrying on board, an innovative instrument, the Miniaturized Electron Proton Telescope (MERiT). The MERiT is a compact low-mass low-power instrument measuring electrons from a few keV to tens of MeV in multiple differential channels. MERiT is optimized to measure electron microbursts with a high time resolution of a few milliseconds. We present and discuss possible future scientific contributions from CeREs.

  9. Calculated limits for particle fluxes in Jupiter's Van Allen belts

    NASA Technical Reports Server (NTRS)

    Haffner, J.

    1972-01-01

    Electron and proton fluxes in Jupiter's radiation belts are calculated, along with the envelopes of dose rates. The following assumptions are made: the particles in the Jupiter belts are influenced only by the magnetic field of the planet; the particles act correspondingly to the particles in the Earth's belts and the Earth's belts can be used as a model; the magnetic field of Jupiter is essentially a dipole; the radiation of a decimetric nature received from Jupiter is synchrotron radiation due to the electrons, and to a first approximation it is emitted isotropically; and the strength of the emission in the decimetric wavelength range gives an upper bound considering how strong the field can be and how many electrons there are. The point dose rates for tissue and 0.1 gram/cm aluminum shielding at about 3 Jupiter radii are 10000 rads/hr for electrons and 1000 rads/hr for protons.

  10. An impenetrable barrier to ultrarelativistic electrons in the Van Allen radiation belts.

    PubMed

    Baker, D N; Jaynes, A N; Hoxie, V C; Thorne, R M; Foster, J C; Li, X; Fennell, J F; Wygant, J R; Kanekal, S G; Erickson, P J; Kurth, W; Li, W; Ma, Q; Schiller, Q; Blum, L; Malaspina, D M; Gerrard, A; Lanzerotti, L J

    2014-11-27

    Early observations indicated that the Earth's Van Allen radiation belts could be separated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. Subsequent studies showed that electrons of moderate energy (less than about one megaelectronvolt) often populate both zones, with a deep 'slot' region largely devoid of particles between them. There is a region of dense cold plasma around the Earth known as the plasmasphere, the outer boundary of which is called the plasmapause. The two-belt radiation structure was explained as arising from strong electron interactions with plasmaspheric hiss just inside the plasmapause boundary, with the inner edge of the outer radiation zone corresponding to the minimum plasmapause location. Recent observations have revealed unexpected radiation belt morphology, especially at ultrarelativistic kinetic energies (more than five megaelectronvolts). Here we analyse an extended data set that reveals an exceedingly sharp inner boundary for the ultrarelativistic electrons. Additional, concurrently measured data reveal that this barrier to inward electron radial transport does not arise because of a physical boundary within the Earth's intrinsic magnetic field, and that inward radial diffusion is unlikely to be inhibited by scattering by electromagnetic transmitter wave fields. Rather, we suggest that exceptionally slow natural inward radial diffusion combined with weak, but persistent, wave-particle pitch angle scattering deep inside the Earth's plasmasphere can combine to create an almost impenetrable barrier through which the most energetic Van Allen belt electrons cannot migrate.

  11. Wave acceleration of electrons in the Van Allen radiation belts.

    PubMed

    Horne, Richard B; Thorne, Richard M; Shprits, Yuri Y; Meredith, Nigel P; Glauert, Sarah A; Smith, Andy J; Kanekal, Shrikanth G; Baker, Daniel N; Engebretson, Mark J; Posch, Jennifer L; Spasojevic, Maria; Inan, Umran S; Pickett, Jolene S; Decreau, Pierrette M E

    2005-09-08

    The Van Allen radiation belts are two regions encircling the Earth in which energetic charged particles are trapped inside the Earth's magnetic field. Their properties vary according to solar activity and they represent a hazard to satellites and humans in space. An important challenge has been to explain how the charged particles within these belts are accelerated to very high energies of several million electron volts. Here we show, on the basis of the analysis of a rare event where the outer radiation belt was depleted and then re-formed closer to the Earth, that the long established theory of acceleration by radial diffusion is inadequate; the electrons are accelerated more effectively by electromagnetic waves at frequencies of a few kilohertz. Wave acceleration can increase the electron flux by more than three orders of magnitude over the observed timescale of one to two days, more than sufficient to explain the new radiation belt. Wave acceleration could also be important for Jupiter, Saturn and other astrophysical objects with magnetic fields.

  12. From the IGY to the IHY: A Changing View of the Van Allen Radiation Belts

    NASA Astrophysics Data System (ADS)

    Hudson, M. K.

    2006-12-01

    Discovery of the Van Allen radiation belts by instrumentation flown on Explorer 1 in 1958 was the first major discovery of the Space Age. A view of the belts as static inner and outer zones of energetic particles with different sources, a double-doughnut encircling the Earth, became iconic to the point that their dynamic behavior and solar connection receded from public awareness and apparent scientific import. Then the Cycle 23 maximum in solar activity arrived in 1989-1991, the first approaching the activity level of the International Geophysical Year of 1957-58, when the Van Allen belts were first discovered. Delay in launch of the NASA-Air Force Combined Radiation Release and Effects Satellite, following the Challenger accident in 1986, led to having the right instruments in the right orbit at the right time to detect prompt injection of outer belt electrons and solar energetic protons into the `slot region' between the inner and outer belts, forming new trapped populations which lasted for years in an otherwise benign location. This event in March 1991, along with the great geomagnetic storm of March 1989, and our increased dependence on space technology since the early Explorer days, led to a resurgence of interest in the Van Allen radiation belts and understanding of their connectivity to the Sun. Additional instrumentation from NASA's International Solar Terrestrial Physics Program, the Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX) and IMAGE spacecraft from the Explorer program, NOAA and DOD spacecraft, and improved worldwide linkages of groundbased measurements have contributed much since 1991 to our understanding of the dynamic characteristics of the Van Allen belts. Further, the presence of continuous solar wind measurements beginning with the launch of WIND in 1994, and SOHO images of Coronal Mass Ejections and coronal hole sources of high speed solar wind flow have filled in the connection with solar activity qualitatively anticipated

  13. Estimates of trapped radiation encountered on low-thrust trajectories through the Van Allen belts

    NASA Technical Reports Server (NTRS)

    Karp, I. M.

    1973-01-01

    Estimates were made of the number of trapped protons and electrons encountered by vehicles on low-thrust trajectories through the Van Allen belts. The estimates serve as a first step in assessing whether these radiations present a problem to on-board sensitive components and payload. The integrated proton spectra and electron spectra are presented for the case of a trajectory described by a vehicle with a constant-thrust acceleration A sub c equal to 0.001 meter/sq sec. This value of acceleration corresponds to a trip time of about 54 days from low earth orbit to synchronous orbit. It is shown that the time spent in the belts and hence the radiation encountered vary nearly inversely with the value of thrust acceleration. Thus, the integrated spectral values presented for the case of A sub c = 0.001 meter/sq sec can be generalized for any other value of thrust acceleration by multiplying them by the factor 0.001/A sub c.

  14. Electron acceleration in the heart of the Van Allen radiation belts.

    PubMed

    Reeves, G D; Spence, H E; Henderson, M G; Morley, S K; Friedel, R H W; Funsten, H O; Baker, D N; Kanekal, S G; Blake, J B; Fennell, J F; Claudepierre, S G; Thorne, R M; Turner, D L; Kletzing, C A; Kurth, W S; Larsen, B A; Niehof, J T

    2013-08-30

    The Van Allen radiation belts contain ultrarelativistic electrons trapped in Earth's magnetic field. Since their discovery in 1958, a fundamental unanswered question has been how electrons can be accelerated to such high energies. Two classes of processes have been proposed: transport and acceleration of electrons from a source population located outside the radiation belts (radial acceleration) or acceleration of lower-energy electrons to relativistic energies in situ in the heart of the radiation belts (local acceleration). We report measurements from NASA's Van Allen Radiation Belt Storm Probes that clearly distinguish between the two types of acceleration. The observed radial profiles of phase space density are characteristic of local acceleration in the heart of the radiation belts and are inconsistent with a predominantly radial acceleration process.

  15. A Century after Van Allen's Birth: Conclusion of Reconnaissance of Radiation Belts in the Solar System

    NASA Astrophysics Data System (ADS)

    Krimigis, S. M.

    2014-12-01

    On May 1, 1958 in the Great Hall of the US National Academy of Sciences, James A. Van Allen, having instrumented Explorer-1 and follow-on satellites with radiation detectors, announced the discovery of intense radiation at high altitudes above Earth. The press dubbed the doughnut-shaped structures "Van Allen Belts" (VAB). Soon thereafter, the search began for VAB at nearby planets. Mariner 2 flew by Venus in 1962 at a distance of 41,000 km, but no radiation was detected. The Mariner 4 mission to Mars did not observe planet-associated increase in radiation, but scaling arguments with Earth's magnetosphere yielded an upper limit to the ratio of magnetic moments of MM/ME < 0.001 (Van Allen et al, 1965). Similarly, the Mariner 5 flyby closer to Venus resulted in a ratio of magnetic moments < 0.001 (Van Allen et al, 1967), dealing a blow to the expectation that all planetary bodies must possess significant VAB. The flyby of Mercury in 1974 by Mariner 10 revealed a weak magnetic field, but the presence of durably trapped higher energy particles remained controversial until MESSENGER in 2011.The first flybys of Jupiter by Pioneers 10, 11 in 1973 and 1974, respectively, measured a plethora of energetic particles in Jupiter's magnetosphere and established the fact that their intensities were rotationally modulated. Later flybys of Jupiter and Saturn by the two Voyagers in 1979 and 1981 revealed that those magnetospheres possessed their own internal plasma source(s) and radiation belts. Subsequent discoveries of Van Allen belts at Uranus and Neptune by Voyager 2 demonstrated that VAB are the rule rather than the exception in planetary environments. We now know from the Voyagers and through Energetic Neutral Atom images from Cassini and IBEX that an immense energetic particle population surrounds the heliosphere itself. Thus, the reconnaissance of radiation belts of our solar system has been completed, some 56 years after the discovery of the Van Allen Belts at Earth.

  16. What have we learned about the energetic particle dynamics in the inner belt and slot region from Van Allen Probes and CSSWE missions?

    NASA Astrophysics Data System (ADS)

    Li, Xinlin; Baker, Daniel N.; Kanekal, Shrikanth; Fennell, Joseph; Selesnick, Richard; Claudepierre, Seth; Blake, Bernard; Zhao, Hong; Jaynes, Allison

    2016-07-01

    Comprehensive measurements of energetic protons (10s of MeV) in the inner belt (L<2) and slot region (2Proton Telescope (REPT) onboard Van Allen Probes, in a geo-transfer-like orbit, revealed new features of these energetic protons in terms of their spectrum distribution, spatial distribution, pitch angle distribution, and their different source populations. Concurrent measurements from the Relativistic Electron-Proton Telescope integrated little experiment (REPTile) on board the Colorado Student Space Weather Experiment (CSSWE) CubeSat, in a highly inclined low Earth orbit, demonstrated that there exist sub-MeV electrons in the inner belt and their flux level is orders of magnitude higher than the background associated with the inner belt protons, while higher energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Analysis on sub-MeV electrons data in the inner belt and slot region from the Magnetic Electron Ion Spectrometer (MagEIS) on board Van Allen Probes revealed rather complicated pitch angle distribution of these energetic electrons, with the 90 deg-minimum (butterfly) pitch angle distribution dominating near the magnetic equator. These are part of a summary of the most recent measurements and understanding of the dynamics of energetic particles in the inner zone and slot region to be exhibited and discussed in this presentation.

  17. A long-lived relativistic electron storage ring embedded in Earth's outer Van Allen belt.

    PubMed

    Baker, D N; Kanekal, S G; Hoxie, V C; Henderson, M G; Li, X; Spence, H E; Elkington, S R; Friedel, R H W; Goldstein, J; Hudson, M K; Reeves, G D; Thorne, R M; Kletzing, C A; Claudepierre, S G

    2013-04-12

    Since their discovery more than 50 years ago, Earth's Van Allen radiation belts have been considered to consist of two distinct zones of trapped, highly energetic charged particles. The outer zone is composed predominantly of megaelectron volt (MeV) electrons that wax and wane in intensity on time scales ranging from hours to days, depending primarily on external forcing by the solar wind. The spatially separated inner zone is composed of commingled high-energy electrons and very energetic positive ions (mostly protons), the latter being stable in intensity levels over years to decades. In situ energy-specific and temporally resolved spacecraft observations reveal an isolated third ring, or torus, of high-energy (>2 MeV) electrons that formed on 2 September 2012 and persisted largely unchanged in the geocentric radial range of 3.0 to ~3.5 Earth radii for more than 4 weeks before being disrupted (and virtually annihilated) by a powerful interplanetary shock wave passage.

  18. A long-lived relativistic electron storage ring embedded in Earth's Outer Van Allen belt

    DOE PAGES

    Baker, D. N.; Kanekal, S. G.; Hoxie, V. C.; ...

    2013-02-28

    Since their discovery over 50 years ago, the Earth’s Van Allen radiation belts are thought to consist of two distinct zones of trapped, highly energetic charged particles. The outer zone is comprised predominantly of mega-electron volt (MeV) electrons that wax and wane in intensity on time scales ranging from hours to days depending primarily on external forcing by the solar wind. Thus, the spatially separated inner zone is comprised of commingled high-energy electrons and very energetic positive ions (mostly protons), the latter being stable in intensity levels over years to decades. In situ energy-specific and temporally resolved spacecraft observations revealmore » an isolated third ring, or torus, of high-energy (E > 2 MeV) electrons that formed on 2 September 2012 and persisted largely unchanged in the geocentric radial range of 3.0 to ~3.5 Earth radii for over four weeks before being disrupted (and virtually annihilated) by a powerful interplanetary shock wave passage.« less

  19. A long-lived relativistic electron storage ring embedded in Earth's Outer Van Allen belt

    SciTech Connect

    Baker, D. N.; Kanekal, S. G.; Hoxie, V. C.; Henderson, M. G.; Li, X.; Spence, H. E.; Elkington, S. R.; Friedel, R. H. W.; Goldstein, J.; Hudson, M. K.; Reeves, G. D.; Thorne, R. M.; Kletzing, C. A.; Claudepierre, S. G.

    2013-02-28

    Since their discovery over 50 years ago, the Earth’s Van Allen radiation belts are thought to consist of two distinct zones of trapped, highly energetic charged particles. The outer zone is comprised predominantly of mega-electron volt (MeV) electrons that wax and wane in intensity on time scales ranging from hours to days depending primarily on external forcing by the solar wind. Thus, the spatially separated inner zone is comprised of commingled high-energy electrons and very energetic positive ions (mostly protons), the latter being stable in intensity levels over years to decades. In situ energy-specific and temporally resolved spacecraft observations reveal an isolated third ring, or torus, of high-energy (E > 2 MeV) electrons that formed on 2 September 2012 and persisted largely unchanged in the geocentric radial range of 3.0 to ~3.5 Earth radii for over four weeks before being disrupted (and virtually annihilated) by a powerful interplanetary shock wave passage.

  20. Unravelling the Complexities of the Earth's Radiation Belts: Findings from the Van Allen Probes mission

    NASA Astrophysics Data System (ADS)

    Mauk, Barry; Fox, Nicola; Kessel, Ramona; Sibeck, David; Kanekal, Shri

    2014-05-01

    Within the first year of Van Allen Probe operations, team members made a series of highly publicized decisive discoveries concerning the structure and evolution of the Earth's radiation belts, the processes that energize particles there, and the locations where they operate. Nevertheless, much more extensive and less publicized findings from the Van Allen Probes suggest that Earth's radiation belts regions remain a highly complex and puzzling place. Although the relation between magnetic storm and radiation belt enhancements and loss has been emphasized, dynamics during non-storm periods has occasionally been shown to be dramatic. While emphasis has been placed on new findings regarding local non-adiabatic energization mechanisms, adiabatic mechanisms have also been shown to be important. Furthermore, the interplay between, and relative importance of, these and other energization processes remain uncertain. The role of seed populations has been highlighted, with some studies pointing to localized mechanisms and others pointing to the role of substorms in transporting and injecting such populations. Here we review some of the less publicized findings and future objectives of the Van Allen Probes mission to get a broader and in-depth view of present understanding of Earth's inner magnetosphere.

  1. High-energy proton radiation belt.

    NASA Technical Reports Server (NTRS)

    White, R. S.

    1973-01-01

    The experiments and theories to explain the high-energy protons trapped in the earth's radiation belt are reviewed. The theory of cosmic ray albedo neutron decay injection of protons into the radiation belt is discussed. Radial diffusion and change in the earth's dipole moment are considered along with losses of protons by ionization and nuclear collision. It is found that the measured albedo neutron escape current is sufficient to supply trapped protons above 30 MeV. The theoretical calculations of the trapped protons are in agreement with the measurements for L less than or equal to 1.7 both on and off the equator. For L greater than or equal to 1.7, additional trapped proton differential energy measurements should be made before the theory can be adequately tested. It appears that an additional loss mechanism such as pitch angle scattering may be required.

  2. Explaining the dynamics of the ultra-relativistic third Van Allen radiation belt

    DOE PAGES

    Mann, I. R.; Ozeke, L. G.; Murphy, K. R.; ...

    2016-06-20

    Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding the recently discovered ultra-relativistic third electron radiation belt. Current theory asserts that loss in the heart of the outer belt, essential to the formation of the third belt, must be controlled by high-frequency plasma wave–particle scattering into the atmosphere, via whistler mode chorus, plasmaspheric hiss, or electromagnetic ion cyclotron waves. However, this has failed to accurately reproduce the third belt. In this paper, using a data-driven, time-dependent specification of ultra-low-frequency (ULF) waves we showmore » for the first time how the third radiation belt is established as a simple, elegant consequence of storm-time extremely fast outward ULF wave transport. High-frequency wave–particle scattering loss into the atmosphere is not needed in this case. Finally, when rapid ULF wave transport coupled to a dynamic boundary is accurately specified, the sensitive dynamics controlling the enigmatic ultra-relativistic third radiation belt are naturally explained.« less

  3. Explaining the dynamics of the ultra-relativistic third Van Allen radiation belt

    SciTech Connect

    Mann, I. R.; Ozeke, L. G.; Murphy, K. R.; Claudepierre, S. G.; Turner, D. L.; Baker, D. N.; Rae, I. J.; Kale, A.; Milling, D. K.; Boyd, A. J.; Spence, H. E.; Reeves, Geoffrey D.; Singer, H. J.; Dimitrakoudis, S.; Daglis, I. A.; Honary, F.

    2016-06-20

    Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding the recently discovered ultra-relativistic third electron radiation belt. Current theory asserts that loss in the heart of the outer belt, essential to the formation of the third belt, must be controlled by high-frequency plasma wave–particle scattering into the atmosphere, via whistler mode chorus, plasmaspheric hiss, or electromagnetic ion cyclotron waves. However, this has failed to accurately reproduce the third belt. In this paper, using a data-driven, time-dependent specification of ultra-low-frequency (ULF) waves we show for the first time how the third radiation belt is established as a simple, elegant consequence of storm-time extremely fast outward ULF wave transport. High-frequency wave–particle scattering loss into the atmosphere is not needed in this case. Finally, when rapid ULF wave transport coupled to a dynamic boundary is accurately specified, the sensitive dynamics controlling the enigmatic ultra-relativistic third radiation belt are naturally explained.

  4. Explaining the dynamics of the ultra-relativistic third Van Allen radiation belt

    NASA Astrophysics Data System (ADS)

    Mann, I. R.; Ozeke, L. G.; Murphy, K. R.; Claudepierre, S. G.; Turner, D. L.; Baker, D. N.; Rae, I. J.; Kale, A.; Milling, D. K.; Boyd, A. J.; Spence, H. E.; Reeves, G. D.; Singer, H. J.; Dimitrakoudis, S.; Daglis, I. A.; Honary, F.

    2016-10-01

    Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding the recently discovered ultra-relativistic third electron radiation belt. Current theory asserts that loss in the heart of the outer belt, essential to the formation of the third belt, must be controlled by high-frequency plasma wave-particle scattering into the atmosphere, via whistler mode chorus, plasmaspheric hiss, or electromagnetic ion cyclotron waves. However, this has failed to accurately reproduce the third belt. Using a data-driven, time-dependent specification of ultra-low-frequency (ULF) waves we show for the first time how the third radiation belt is established as a simple, elegant consequence of storm-time extremely fast outward ULF wave transport. High-frequency wave-particle scattering loss into the atmosphere is not needed in this case. When rapid ULF wave transport coupled to a dynamic boundary is accurately specified, the sensitive dynamics controlling the enigmatic ultra-relativistic third radiation belt are naturally explained.

  5. Impacts of intense inward and outward ULF wave radial diffusion on the Van Allen belts

    NASA Astrophysics Data System (ADS)

    Mann, Ian; Ozeke, Louis; Rae, I. Jonathan; Murphy, Kyle

    2016-07-01

    During geomagnetic storms, the power in ultra-low frequency (ULF) waves can be orders of magnitude larger than that predicted by statistics determined from an entire solar cycle. This is especially true during the main phase and early recovery phase. These periods of enhanced storm-time ULF wave power can have significant impacts on the morphology and structure of the Van Allen belts. Either fast inward or outward radial diffusion can result, depending on the profiles of the electron phase space density and the outer boundary condition at the edge of the belts. Small changes in the time sequence of powerful ULF waves, and the time sequence of any magnetopause shadowing or the recovery of plamasheet sources relative to the ULF wave occurrence, have a remarkable impact on the resulting structure of the belts. The overall impact of the enhanced ULF wave power is profound, but the response can be very different depending on the available source flux in the plasmasheet. We review these impacts by examining ultra-relativistic electron dynamics during seemingly different storms during the Van Allen Probe era, including during the Baker et al. third radiation belt, and show the observed behaviour can be largely explained by differences in the time sequence of events described above.

  6. An extreme distortion of the Van Allen belt arising from the 'Hallowe'en' solar storm in 2003.

    PubMed

    Baker, D N; Kanekal, S G; Li, X; Monk, S P; Goldstein, J; Burch, J L

    2004-12-16

    The Earth's radiation belts--also known as the Van Allen belts--contain high-energy electrons trapped on magnetic field lines. The centre of the outer belt is usually 20,000-25,000 km from Earth. The region between the belts is normally devoid of particles, and is accordingly favoured as a location for spacecraft operation because of the benign environment. Here we report that the outer Van Allen belt was compressed dramatically by a solar storm known as the 'Hallowe'en storm' of 2003. From 1 to 10 November, the outer belt had its centre only approximately 10,000 km from Earth's equatorial surface, and the plasmasphere was similarly displaced inwards. The region between the belts became the location of high particle radiation intensity. This remarkable deformation of the entire magnetosphere implies surprisingly powerful acceleration and loss processes deep within the magnetosphere.

  7. Explaining occurrences of auroral kilometric radiation in Van Allen radiation belts

    NASA Astrophysics Data System (ADS)

    Xiao, Fuliang; Zhou, Qinghua; Su, Zhenpeng; He, Zhaoguo; Yang, Chang; Liu, Si; He, Yihua; Gao, Zhonglei

    2016-12-01

    Auroral kilometric radiation (AKR) is a strong terrestrial radio emission and dominates at higher latitudes because of reflection in vicinities of the source cavity and plasmapause. Recently, Van Allen Probes have observed occurrences of AKR emission in the equatorial region of Earth's radiation belts but its origin still remains an open question. Equatorial AKR can produce efficient acceleration of radiation belt electrons and is a risk to space weather. Here we report high-resolution observations during two small storm periods 4-6 April and 18-20 May 2013 and show, using a 3-D ray tracing simulation, that AKR can propagate downward all the way into the equatorial plane in the radiation belts under appropriate conditions. The simulated results can successfully explain the observed AKR's spatial distribution and frequency range, and the current results have a wide application to all other magnetized astrophysical objects in the universe.

  8. Nonlinear wave-particle interactions in the outer radiation belts: Van Allen Probes results

    NASA Astrophysics Data System (ADS)

    Agapitov, Oleksiy; Mozer, Forrest; Artemyev, Anton; Drake, James; Vasko, Ivan

    2016-10-01

    Huge numbers of different nonlinear structures (double layers, electron holes, non-linear whistlers, etc. referred to as Time Domain Structures - TDS) have been observed by the electric field experiment on board the Van Allen Probes. A large part of the observed non-linear structures are associated with whistler waves and some of them can be directly driven by whistlers. Observations of electron velocity distributions and chorus waves by the Van Allen Probe B provided long-lasting signatures of electron Landau resonant interactions with oblique chorus waves in the outer radiation belt. In the inhomogeneous geomagnetic field, such resonant interactions then lead to the formation of a plateau in the parallel (with respect to the geomagnetic field) velocity distribution due to trapping of electrons into the wave effective potential. The feedback from trapped particles provides steepening of parallel electric field and development of TDS seeded from initial whistler structure (well explained in terms of Particle-In-Cell model). The decoupling of the whistler wave and the nonlinear electrostatic component is shown in PIC simulation in the inhomogeneous magnetic field system and are observed by the Van Allen Probes in the radiation belts.

  9. Very energetic protons in Saturn's radiation belt

    NASA Technical Reports Server (NTRS)

    Fillius, W.; Mcilwain, C.

    1980-01-01

    Very energetic protons are trapped in the inner Saturnian radiation belt. The University of California at San Diego instrument on Pioneer 11 has definitely identified protons of energy greater than 80 MeV on channel M3 and has tentatively detected protons of energy greater than 600 MeV on channel C3. The spatial distribution of the protons is distinct from that of the trapped electrons, the main difference being that the protons are strongly absorbed by the innermost moons and that the electrons are not. The source strength for injecting protons by the decay of cosmic ray albedo neutrons generated in the rings of Saturn has been estimated. The required proton lifetime is approximately 20 years.

  10. Observation of plasma depletions in outer radiation belt by Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Lee, J.; Kim, K.; Lee, E.; Kim, Y.; Park, Y.; Parks, G. K.; Sibeck, D. G.

    2013-12-01

    Van Allen Probes (RBSP) observed plasma fine structures in the outer radiation belt during storm time on 14 November 2012. Five plasma depletion regions are clearly identified by VAP_A and VAP_B from 02:00UT to 04:45UT by particle instrument suite that can measure electrons and ions in a wide energy range, from 20 eV to 10 MeV. The plasma flux density dramatically decreases about 2 - 3 orders of magnitude in the depletion regions regardless of energy and particle species. Our analysis shows the plasma cavities are formed at the boundary of trapped and injected particle current. The total plasma pressures inside the depletion regions are much smaller than outside, implying unstable structures. It seems that this structures appear unusually only for storm main phase. During strong storm event, geomagnetic field is stretched and low plasma density region (lobe) moves to low latitude, this event could be analyzed by lobe region crossing of spacecraft. However, to explain temporal sequences of this event, we should assume large fluctuation of lobe boundary. Another possible analysis is plasma bubble generated in the tail region. The bubble model proposed to explain plasma transportation form tail to near Earth region in 1980s. While the bubble model reasonably explain the spatial and temporal structures observed by Van Allen probes, we cannot completely rule out the lobe region crossing model. In this presentation, we shall discuss about the characteristics of the plasma density cavities first observed by Van Allen Probes.

  11. On the generation of large amplitude spiky solitons by ultralow frequency earthquake emission in the Van Allen radiation belt

    SciTech Connect

    Mofiz, U. A.

    2006-08-15

    The parametric coupling between earthquake emitted circularly polarized electromagnetic radiation and ponderomotively driven ion-acoustic perturbations in the Van Allen radiation belt is considered. A cubic nonlinear Schroedinger equation for the modulated radiation envelope is derived, and then solved analytically. For ultralow frequency earthquake emissions large amplitude spiky supersonic bright solitons or subsonic dark solitons are found to be generated in the Van Allen radiation belt, detection of which can be a tool for the prediction of a massive earthquake may be followed later.

  12. Wave-driven butterfly distribution of Van Allen belt relativistic electrons

    SciTech Connect

    Xiao, Fuliang; Yang, Chang; Su, Zhenpeng; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.

    2015-10-05

    Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day–night asymmetry in Earth’s magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28 June 2013 geomagnetic storm. In conclusion, simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. Finally, the current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons.

  13. Wave-driven butterfly distribution of Van Allen belt relativistic electrons.

    PubMed

    Xiao, Fuliang; Yang, Chang; Su, Zhenpeng; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Baker, D N; Spence, H E; Funsten, H O; Blake, J B

    2015-10-05

    Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day-night asymmetry in Earth's magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28 June 2013 geomagnetic storm. Simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. The current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons.

  14. Wave-driven butterfly distribution of Van Allen belt relativistic electrons

    NASA Astrophysics Data System (ADS)

    Xiao, Fuliang; Yang, Chang; Su, Zhenpeng; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.

    2015-10-01

    Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day-night asymmetry in Earth's magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28 June 2013 geomagnetic storm. Simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. The current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons.

  15. Wave-driven butterfly distribution of Van Allen belt relativistic electrons

    PubMed Central

    Xiao, Fuliang; Yang, Chang; Su, Zhenpeng; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.

    2015-01-01

    Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day–night asymmetry in Earth's magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28 June 2013 geomagnetic storm. Simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. The current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons. PMID:26436770

  16. The Relativistic Proton Spectrometer (RPS) for the Radiation Belt Storm Probes Mission

    NASA Astrophysics Data System (ADS)

    Mazur, J. E.; Friesen, L.; Lin, A.; Mabry, D.; Katz, N.; Dotan, Y.; George, J. S.; Blake, J. B.; Looper, M. D.; Redding, M.; O'Brien, P. P.; Cha, J.; Birkitt, A.; Carranza, P.; Lalic, M.; Fuentes, F.; Galvan, R.; McNab, M. C.

    2012-12-01

    The Relativistic Proton Spectrometer (RPS) on the Radiation Belt Storm Probes spacecraft is a particle spectrometer designed to measure the flux, angular distribution, and energy spectrum of protons from ~60 MeV to ~2000 MeV. RPS will investigate decades-old questions about the inner Van Allen belt proton environment: a nearby region of space that is relatively unexplored because of the hazards of spacecraft operation there and the difficulties in obtaining accurate proton measurements in an intense penetrating background. RPS is designed to provide the accuracy needed to answer questions about the sources and losses of the inner belt protons and to obtain the measurements required for the next-generation models of trapped protons in the magnetosphere. In addition to detailed information for individual protons, RPS features count rates at a 1-second timescale, internal radiation dosimetry, and information about electrostatic discharge events on the RBSP spacecraft that together will provide new information about space environmental hazards in the Earth's magnetosphere.

  17. The Relativistic Proton Spectrometer (RPS) for the Radiation Belt Storm Probes Mission

    NASA Astrophysics Data System (ADS)

    Mazur, J.; Friesen, L.; Lin, A.; Mabry, D.; Katz, N.; Dotan, Y.; George, J.; Blake, J. B.; Looper, M.; Redding, M.; O'Brien, T. P.; Cha, J.; Birkitt, A.; Carranza, P.; Lalic, M.; Fuentes, F.; Galvan, R.; McNab, M.

    2013-11-01

    The Relativistic Proton Spectrometer (RPS) on the Radiation Belt Storm Probes spacecraft is a particle spectrometer designed to measure the flux, angular distribution, and energy spectrum of protons from ˜60 MeV to ˜2000 MeV. RPS will investigate decades-old questions about the inner Van Allen belt proton environment: a nearby region of space that is relatively unexplored because of the hazards of spacecraft operation there and the difficulties in obtaining accurate proton measurements in an intense penetrating background. RPS is designed to provide the accuracy needed to answer questions about the sources and losses of the inner belt protons and to obtain the measurements required for the next-generation models of trapped protons in the magnetosphere. In addition to detailed information for individual protons, RPS features count rates at a 1-second timescale, internal radiation dosimetry, and information about electrostatic discharge events on the RBSP spacecraft that together will provide new information about space environmental hazards in the Earth's magnetosphere.

  18. Understanding Earth's radiation belt electron dynamics: Van Allen Probes observations and simulations

    NASA Astrophysics Data System (ADS)

    Li, Wen; Ma, Qianli; Thorne, Richard; Bortnik, Jacob; Zhang, Xiaojia

    2016-10-01

    Various physical processes are known to cause acceleration, loss, and transport of energetic electrons in the Earth's radiation belts, but their quantitative roles in different time and space need further investigation. In the present paper, we evaluate the relative roles of various physical processes during geomagnetic storms using a 3D diffusion simulation. By quantitatively comparing the electron evolution observed by Van Allen Probes and simulation, we found that whistler-mode chorus waves play a critical role in accelerating electrons up to several MeV through efficient energy diffusion. By only including radial diffusion driven by ultra-low-frequency waves, the simulation underestimates the observed electron acceleration, while radial diffusion plays an important role in redistributing electrons. Although an additional loss process is required to fully explain the overestimated electron fluxes at multi-MeV, the combined physical processes of radial diffusion and scattering by whistler-mode waves reproduce the observed electron dynamics remarkably well, suggesting that quasi-linear diffusion theory is reasonable to evaluate radiation belt electron dynamics, and the importance of nonlinear wave-particle interaction may still remain as an open question. We would like to acknowledge AFOSR Award FA9550-15-1-0158, NASA Grants NNX15AI96G, NNX15AF61G, and the NSF Grant AGS 1564510 for supporting this research.

  19. Variation of energetic electron flux in Earth's radiation belts based on Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Tang, Rongxin; Zhong, Zhihong; Yu, Deyin

    2016-04-01

    The Earth's radiation belts have been an important research topic of solar-terrestrial physics from 1958. In 2012, Van Allen Probes (VAP) were launched into near-equatorial orbit and provide very good in-situ observations of energetic particles in inner magnetosphere. Since magnetospheric substorm can cause the severe disturbance of the Earth's megnetospheric environment, here we focus on the characteristics of energetic electron fluxes in the radiation belts during substorm time and non-storm time. Energetic electron data observed by the Magnetic Electron Ion Spectrometer (MagEIS) and Energetic Particle Composition and Thermal Plasma Suite (ECT) of VAP during 2012 to 2014 are carefully analyzed. We select portions of energetic electron data from substorm onset phase, growth phase, recovery phase, and quiet time, and make a comparisons with theoretical computations. We find that the electron differential fluxes present E-1 shape at lower energies (<1MeV), and have a sharp transition with steeper slopes at high energies for large L-shells, which are in coincidence with Mauk's model [Mauk et al., 2010].

  20. Recent Results from the Relativistic Electron Proton Telescope (REPT) onboard the Van Allen Probes Mission

    NASA Astrophysics Data System (ADS)

    Kanekal, S. G.; Baker, D. N.; Elkington, S. R.; Hoxie, V. C.; Li, X.; Spence, H. E.

    2013-05-01

    We describe recent results from the REPT instruments on board Van Allen Probes mission launched on 30 August 2012. The twin spacecraft comprising the Van Allen probes mission are identically instrumented and carry a comprehensive suite of sensors characterizing magnetospheric charged particle populations, electric and magnetic fields and plasma waves. The REPT instruments comprise a well-shielded silicon solid state detector stack, with a state of the art electronics and measure electrons of ~1.5 to > 20 MeV and protons of ~17 to > 100 MeV. The instruments were commissioned 3 days after launch and continue to provide high quality measurements. We describe the Van Allen probes and the REPT instrument and report on the new and unexpected features of the outer zone electron populations observed by REPT.

  1. How quickly, how deeply, and how strongly can dynamical outer boundary conditions impact Van Allen radiation belt morphology?

    NASA Astrophysics Data System (ADS)

    Mann, Ian R.; Ozeke, Louis G.

    2016-06-01

    Here we examine the speed, strength, and depth of the coupling between dynamical variations of ultrarelativistic electron flux at the outer boundary and that in the heart of the outer radiation belt. Using ULF wave radial diffusion as an exemplar, we show how changing boundary conditions can completely change belt morphology even under conditions of identical wave power. In the case of ULF wave radial diffusion, the temporal dynamics of a new source population or a sink of electron flux at the outer plasma sheet boundary can generate a completely opposite response which reaches deep into the belt under identical ULF wave conditions. Very significantly, here we show that such coupling can occur on timescales much faster than previously thought. We show that even on timescales ~1 h, changes in the outer boundary electron population can dramatically alter the radiation belt flux in the heart of the belt. Importantly, these flux changes can at times occur on timescales much faster than the L shell revisit time obtained from elliptically orbiting satellites such as the Van Allen Probes. We underline the importance of such boundary condition effects when seeking to identify the physical processes which explain the dominant behavior of the Van Allen belts. Overall, we argue in general that the importance of temporal changes in the boundary conditions is sometimes overlooked in comparison to the pursuit of (ever) increasingly accurate estimates of wave power and other wave properties used in empirical representations of wave transport and diffusion rates.

  2. Estimates of Total Radiation Belt Electron Content (TRBEC) and its Time Evolution using the RBSP-ECT Instrument Suite on the Van Allen Probes Mission

    NASA Astrophysics Data System (ADS)

    Spence, H.; Boyd, A. J.; Huang, C.; Smith, S. S.; Henderson, M. G.; Friedel, R. H.; Larsen, B.; Reeves, G. D.; Blake, J. B.; Claudepierre, S. G.; Fennell, J. F.; Baker, D. N.; Kanekal, S. G.

    2013-12-01

    Using measurements from the two-spacecraft Van Allen Probes mission we estimate the total radiation belt electron content (TRBEC) as a simple, global quantitative measure of radiation belt intensity. The two identically-instrumented spacecraft provide comprehensive energy and pitch angle coverage of radiation belt electrons near the magnetic equator throughout the inner magnetosphere, an advantage over earlier studies by Baker et al. (2004) and Selesnick and Kanekal (2009) that estimated similar quantities in LEO or in high-altitude polar orbits. We use electron measurements from the Radiation Belt Storm Probes (RBSP) Energetic Particle, Composition, and Thermal Plasma (ECT) suite to identify both the electron seed populations (a few 10's to a few 100's keV) as well as radiation belt electron populations (> ~ 500 keV) with the Magnetic Electron Ion Spectrometer (MagEIS) and the Relativistic Electron Proton Telescope (REPT) sensors. MagEIS provides the electron seed population measurements; MagEIS and REPT together provide the core radiation belt and ultra-relativistic electron populations. Using energy-resolved, locally-measured pitch angle distributions of electrons as a function of L, we estimate the equatorial distribution and then integrate the electrons over energy and pitch angle throughout the spatial volume to establish the TRBEC for both the electron seed and the core populations. Finally, we show how TRBEC varies as a function of time over the course of the mission, compare these variations to other quantitative measures of inner magnetospheric dynamism (e.g., Dst) and solar wind drivers, compare the seed to core TRBEC values and its time evolution, as well as compare to prior quantitative estimates of radiation belt electron content.

  3. Revealing the generation of extremely low frequency chorus in Van Allen radiation belts

    DOE PAGES

    Xiao, Fuliang; Liu, Si; Tao, Xin; ...

    2017-03-02

    Recent studies have shown that chorus can efficiently accelerate the outer radiation belt electrons to relativistic energies. Chorus, previously often observed above 0.1 equatorial electron gyrofrequency fce, was generated by energetic electrons originating from Earth's plasmasheet. Chorus below 0.1 fce has seldom been reported until the recent data from Van Allen Probes but its origin has not been revealed so far. Because electron resonant energy can approach the relativistic level at extremely low frequency relativistic effects should be considered in the formula for whistler-mode wave growth rate. Here we report high-resolution observations during the 14 October 2014 small storm andmore » firstly demonstrate, using a fully relativistic simulation, that electrons with the high energy tail population and relativistic pitch angle anisotropy can provide free energy sufficient for generating chorus below 0.1 fce. The simulated wave growth displays a very similar pattern to the observations. Finally, the current results can be applied to Jupiter, Saturn and other magnetized planets.« less

  4. Wave-driven butterfly distribution of Van Allen belt relativistic electrons

    DOE PAGES

    Xiao, Fuliang; Yang, Chang; Su, Zhenpeng; ...

    2015-10-05

    Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day–night asymmetry in Earth’s magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28more » June 2013 geomagnetic storm. In conclusion, simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. Finally, the current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons.« less

  5. The seasonal dependence of relativistic electron fluxes in the Earth's outer van Allen Belt

    NASA Astrophysics Data System (ADS)

    Kanekal, S. G.; Baker, D. N.; McPherron, R.

    2007-12-01

    It is well known that geomagnetic activity shows a marked seasonal dependence. This effect has been attributed to the seasonal variation of the Earth's dipole tilt angle exposing the magnetosphere to an increased southward component of the interplanetary field (the Russell-McPherron effect) or an increased solar wind velocity (the axial/equinoctial effect). We examine the seasonal dependence of relativistic electron fluxes in the Earth's outer Van Allen belt. An earlier investigation by Baker et. al., (1999) found that the relativistic electron fluxes do show a strong seasonal dependence with the equinoctial electron fluxes being almost three times higher than the solstitial fluxes. We extend this previous investigation using data obtained by sensors onboard SAMPEX. This study of the seasonal dependence is based on data with a higher time resolution as compared to the earlier study. The results of our analysis show that the peak electron fluxes are shifted in time from the nominal equinoctial times. We discuss some possible implications of our observations in the context of electron energization in the Earth's magnetosphere. Baker, D.N., S.G. Kanekal, T.I. Pulkkinen, and J.B. Blake, Equinoctial and solstitial averages of magnetospheric relativistic electrons: A strong semiannual modulation, Geophys. Res. Lett., 26, No. 20, 3193-3196, 1999.

  6. Science Goals and Overview of the Radiation Belt Storm Probes (RBSP) Energetic Particle, Composition, and Thermal Plasma (ECT) Suite on NASA's Van Allen Probes Mission

    NASA Astrophysics Data System (ADS)

    Spence, H. E.; Reeves, G. D.; Baker, D. N.; Blake, J. B.; Bolton, M.; Bourdarie, S.; Chan, A. A.; Claudepierre, S. G.; Clemmons, J. H.; Cravens, J. P.; Elkington, S. R.; Fennell, J. F.; Friedel, R. H. W.; Funsten, H. O.; Goldstein, J.; Green, J. C.; Guthrie, A.; Henderson, M. G.; Horne, R. B.; Hudson, M. K.; Jahn, J.-M.; Jordanova, V. K.; Kanekal, S. G.; Klatt, B. W.; Larsen, B. A.; Li, X.; MacDonald, E. A.; Mann, I. R.; Niehof, J.; O'Brien, T. P.; Onsager, T. G.; Salvaggio, D.; Skoug, R. M.; Smith, S. S.; Suther, L. L.; Thomsen, M. F.; Thorne, R. M.

    2013-11-01

    The Radiation Belt Storm Probes (RBSP)-Energetic Particle, Composition, and Thermal Plasma (ECT) suite contains an innovative complement of particle instruments to ensure the highest quality measurements ever made in the inner magnetosphere and radiation belts. The coordinated RBSP-ECT particle measurements, analyzed in combination with fields and waves observations and state-of-the-art theory and modeling, are necessary for understanding the acceleration, global distribution, and variability of radiation belt electrons and ions, key science objectives of NASA's Living With a Star program and the Van Allen Probes mission. The RBSP-ECT suite consists of three highly-coordinated instruments: the Magnetic Electron Ion Spectrometer (MagEIS), the Helium Oxygen Proton Electron (HOPE) sensor, and the Relativistic Electron Proton Telescope (REPT). Collectively they cover, continuously, the full electron and ion spectra from one eV to 10's of MeV with sufficient energy resolution, pitch angle coverage and resolution, and with composition measurements in the critical energy range up to 50 keV and also from a few to 50 MeV/nucleon. All three instruments are based on measurement techniques proven in the radiation belts. The instruments use those proven techniques along with innovative new designs, optimized for operation in the most extreme conditions in order to provide unambiguous separation of ions and electrons and clean energy responses even in the presence of extreme penetrating background environments. The design, fabrication and operation of ECT spaceflight instrumentation in the harsh radiation belt environment ensure that particle measurements have the fidelity needed for closure in answering key mission science questions. ECT instrument details are provided in companion papers in this same issue. In this paper, we describe the science objectives of the RBSP-ECT instrument suite on the Van Allen Probe spacecraft within the context of the overall mission objectives

  7. Van Allen Probes Mission Space Academy: Educating middle school students about Earth's mysterious radiation belts

    NASA Astrophysics Data System (ADS)

    Butler, L.; Turney, D.; Matiella Novak, A.; Smith, D.; Simon, M.

    2013-12-01

    How's the weather in space? Why on Earth did NASA send two satellites above Earth to study radiation belts and space weather? To learn the answer to questions about NASA's Van Allen Probes mission, 450 students and their teachers from Maryland middle schools attended Space Academy events highlighting the Van Allen Probes mission. Sponsored by the Applied Physics Laboratory (APL) and Discovery Education, the events are held at the APL campus in Laurel, MD. Space Academies take students and teachers on behind-the-scenes exploration of how spacecraft are built, what they are designed to study, and introduces them to the many professionals that work together to create some of NASA's most exciting projects. Moderated by a public relations representative in the format of an official NASA press conference, the daylong event includes a student press conference with students as reporters and mission experts as panelists. Lunch with mission team members gives students a chance to ask more questions. After lunch, students don souvenir clean room suits, enjoy interactive science demonstrations, and tour APL facilities where the Van Allen Probes were built and tested before launch. Students may even have an opportunity to peek inside a clean room to view spacecraft being assembled. Prior to the event, teachers are provided with classroom activities, lesson plans, and videos developed by APL and Discovery Education to help prepare students for the featured mission. The activities are aligned to National Science Education Standards and appropriate for use in the classroom. Following their visit, student journalists are encouraged to write a short article about their field trip; selections are posted on the Space Academy web site. Designed to engage, inspire, and influence attitudes about space science and STEM careers, Space Academies provide an opportunity to attract underserved populations and emphasize that space science is for everyone. Exposing students to a diverse group of

  8. A Comparison of Van Allen Belt Radiation Environment Modeling Programs: AE8/AP8 Legacy, AE9/AP9, and SPENVIS

    NASA Technical Reports Server (NTRS)

    Reed, Evan; Pellish, Jonathan

    2016-01-01

    In the space surrounding Earth there exists an active radiation environment consisting mostly of electrons and protons that have been trapped by Earths magnetic field. This radiation, also known as the Van Allen Belts, has the potential to damage man-made satellites in orbit; thus, proper precautions must be taken to shield NASA assets from this phenomenon. Data on the Van Allen Belts has been collected continuously by a multitude of space-based instruments since the beginning of space exploration. Subsequently, using theory to fill in the gaps in the collected data, computer models have been developed that take in the orbital information of a hypothetical mission and output the expected particle fluence and flux for that orbit. However, as new versions of the modeling system are released, users are left wondering how the new version differs from the old. Therefore, we performed a comparison of three different editions of the modeling system: AE8/AP8 (legacy), which is included in the model 9 graphical user interface as an option for ones calculations, AE9/AP9, and the Space Environment Information System (SPENVIS), which is an online-based form of AE8/AP8 developed by NASA and the European Space Agency that changed the code to allow the program to extrapolate data to predict fluence and flux at higher energies. Although this evaluation is still ongoing, it is predicted that the model 8 (legacy) and SPENVIS version will have identical outputs with the exception of the extended energy levels from SPENVIS, while model 9 will provide different fluences than model 8 based on additional magnetic field descriptions and on-orbit data.

  9. Investigation of solar wind driver effects on electron acceleration and loss in the outer Van Allen belt

    NASA Astrophysics Data System (ADS)

    Katsavrias, Christos; Li, Wen; Daglis, Ioannis A.; Papadimitriou, Constantinos; Georgiou, Marina; Dimitrakoudis, Stavros

    2016-07-01

    We have investigated the response of the outer Van Allen belt electrons to various types of solar wind and internal magnetospheric forcing - in particular to Interplanetary Coronal Mass Ejections (ICMEs), to High Speed Streams (HSS), to geospace magnetic storms of different intensities and to intense magnetospheric substorms. We have employed multi-point particle and field observations in the inner magnetosphere (both in-situ and through ground-based remote sensing), including the Cluster, THEMIS, Van Allen Probes and GOES constellations, the XMM and INTEGRAL spacecraft, and the CARISMA and IMAGE ground magnetometer arrays. The data provide a broad range of particle energies and a wide radial and azimuthal spatial coverage. Observations show that losses of equatorially mirroring electrons are primarily caused by magnetopause shadowing which in turn is achieved by outward diffusion driven by Pc5 ULF waves. Chorus wave activity, on the other hand, seems to be responsible for electron enhancements in the outer radiation belt even in the presence of pronounced outward diffusion.

  10. Visualization of Radiation Belts from REPT Data

    NASA Video Gallery

    This visualization, created using actual data from the Relativistic Electron-Proton Telescopes (REPT) on NASA’s Van Allen Probes, clearly shows the emergence of new third belt and second slot reg...

  11. Van Allen Probes observations of prompt MeV radiation belt electron acceleration in nonlinear interactions with VLF chorus

    NASA Astrophysics Data System (ADS)

    Foster, J. C.; Erickson, P. J.; Omura, Y.; Baker, D. N.; Kletzing, C. A.; Claudepierre, S. G.

    2017-01-01

    Prompt recovery of MeV (millions of electron Volts) electron populations in the poststorm core of the outer terrestrial radiation belt involves local acceleration of a seed population of energetic electrons in interactions with VLF chorus waves. Electron interactions during the generation of VLF rising tones are strongly nonlinear, such that a fraction of the relativistic electrons at resonant energies are trapped by waves, leading to significant nonadiabatic energy exchange. Through detailed examination of VLF chorus and electron fluxes observed by Van Allen Probes, we investigate the efficiency of nonlinear processes for acceleration of electrons to MeV energies. We find through subpacket analysis of chorus waveforms that electrons with initial energy of hundreds of keV to 3 MeV can be accelerated by 50 keV-200 keV in resonant interactions with a single VLF rising tone on a time scale of 10-100 ms.

  12. Wave-induced loss of ultra-relativistic electrons in the Van Allen radiation belts.

    PubMed

    Shprits, Yuri Y; Drozdov, Alexander Y; Spasojevic, Maria; Kellerman, Adam C; Usanova, Maria E; Engebretson, Mark J; Agapitov, Oleksiy V; Zhelavskaya, Irina S; Raita, Tero J; Spence, Harlan E; Baker, Daniel N; Zhu, Hui; Aseev, Nikita A

    2016-09-28

    The dipole configuration of the Earth's magnetic field allows for the trapping of highly energetic particles, which form the radiation belts. Although significant advances have been made in understanding the acceleration mechanisms in the radiation belts, the loss processes remain poorly understood. Unique observations on 17 January 2013 provide detailed information throughout the belts on the energy spectrum and pitch angle (angle between the velocity of a particle and the magnetic field) distribution of electrons up to ultra-relativistic energies. Here we show that although relativistic electrons are enhanced, ultra-relativistic electrons become depleted and distributions of particles show very clear telltale signatures of electromagnetic ion cyclotron wave-induced loss. Comparisons between observations and modelling of the evolution of the electron flux and pitch angle show that electromagnetic ion cyclotron waves provide the dominant loss mechanism at ultra-relativistic energies and produce a profound dropout of the ultra-relativistic radiation belt fluxes.

  13. Wave-induced loss of ultra-relativistic electrons in the Van Allen radiation belts

    NASA Astrophysics Data System (ADS)

    Shprits, Yuri Y.; Drozdov, Alexander Y.; Spasojevic, Maria; Kellerman, Adam C.; Usanova, Maria E.; Engebretson, Mark J.; Agapitov, Oleksiy V.; Zhelavskaya, Irina S.; Raita, Tero J.; Spence, Harlan E.; Baker, Daniel N.; Zhu, Hui; Aseev, Nikita A.

    2016-09-01

    The dipole configuration of the Earth's magnetic field allows for the trapping of highly energetic particles, which form the radiation belts. Although significant advances have been made in understanding the acceleration mechanisms in the radiation belts, the loss processes remain poorly understood. Unique observations on 17 January 2013 provide detailed information throughout the belts on the energy spectrum and pitch angle (angle between the velocity of a particle and the magnetic field) distribution of electrons up to ultra-relativistic energies. Here we show that although relativistic electrons are enhanced, ultra-relativistic electrons become depleted and distributions of particles show very clear telltale signatures of electromagnetic ion cyclotron wave-induced loss. Comparisons between observations and modelling of the evolution of the electron flux and pitch angle show that electromagnetic ion cyclotron waves provide the dominant loss mechanism at ultra-relativistic energies and produce a profound dropout of the ultra-relativistic radiation belt fluxes.

  14. Wave-induced loss of ultra-relativistic electrons in the Van Allen radiation belts

    PubMed Central

    Shprits, Yuri Y.; Drozdov, Alexander Y.; Spasojevic, Maria; Kellerman, Adam C.; Usanova, Maria E.; Engebretson, Mark J.; Agapitov, Oleksiy V.; Zhelavskaya, Irina S.; Raita, Tero J.; Spence, Harlan E.; Baker, Daniel N.; Zhu, Hui; Aseev, Nikita A.

    2016-01-01

    The dipole configuration of the Earth's magnetic field allows for the trapping of highly energetic particles, which form the radiation belts. Although significant advances have been made in understanding the acceleration mechanisms in the radiation belts, the loss processes remain poorly understood. Unique observations on 17 January 2013 provide detailed information throughout the belts on the energy spectrum and pitch angle (angle between the velocity of a particle and the magnetic field) distribution of electrons up to ultra-relativistic energies. Here we show that although relativistic electrons are enhanced, ultra-relativistic electrons become depleted and distributions of particles show very clear telltale signatures of electromagnetic ion cyclotron wave-induced loss. Comparisons between observations and modelling of the evolution of the electron flux and pitch angle show that electromagnetic ion cyclotron waves provide the dominant loss mechanism at ultra-relativistic energies and produce a profound dropout of the ultra-relativistic radiation belt fluxes. PMID:27678050

  15. A plan to clear energetic protons from the radiation belt

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-11-01

    The Earth's radiation belts have been a known hazard to satellites since at least 1962, when an American high-altitude nuclear weapons test named Starfish Prime produced an artificial belt that disabled the first commercial communications satellite, TelStar 1. In the years since the Cold War, thousands of satellites have been put into orbit, and surface charging, high-energy protons, high-energy electrons known as "killer electrons," and other hazards of the inner magnetosphere have continued to take their toll. Satellites can be hardened against these radiation hazards, but some researchers have recently floated a more radical idea: If specially designed transmitters are put into space and set to emit tightly tuned waves, known as electromagnetic ion cyclotron (EMIC) waves, they could potentially push the highly energetic protons out of the Earth's inner radiation belt, clearing the satellite's path.

  16. Dynamics of the low altitude secondary proton radiation belt.

    PubMed

    Gusev, A A; Kohno, T; Spjeldvik, W N; Martin, I M; Pugacheva, G I; Turtelli, A

    1998-01-01

    At the interface between the upper atmosphere and the radiation belt region, there exists a secondary radiation belt consisting mainly of energetic ions that have become neutralized in the ring current and the main radiation belt and then re-ionized by collisions in the inner exosphere. The time history of the proton fluxes in the 0.64-35 MeV energy range was traced in the equatorial region beneath the main radiation belts during the three year period from 21 February 1984 to 26 March 1987 using data obtained with the HEP experiment on board the Japanese OHZORA satellite. During most of this period a fairly small proton flux of -1.2 cm-2 S-1 sr-1 was detected on geomagnetic field lines in the range 1.05 < L < 1.15. We report a few surprisingly deep and rapid flux decreases (flux reduction by typically two orders of magnitude). These flux decreases were also long in duration (lasting up to three months). We also registered abrupt flux increases where the magnitude of the proton flux enhancements could reach three orders of magnitude with an enhancement duration of 1-3 days. Possible reasons for these unexpected phenomena are discussed.

  17. Electron and proton flux models for Jupiter's radiation belts

    NASA Technical Reports Server (NTRS)

    Klopp, D. A.

    1972-01-01

    Estimates of the energetic particle distribution in Jupiter's radiation belts are presented and are compared with previous estimates. Mathematical expressions are developed for the equatorial electron and proton fluxes, shielded electron and proton dose rates, and radiation lifetimes of electronic circuits. It is calculated that a 1 g/sq cm aluminum shield will screen out all protons of energy less than 27.5 MeV, and a 2 g/sq cm shield will screen out protons less than 40.6 MeV. The radiation lifetimes are based on a maximum permissible dose value of 10 million rads, a value 1/2 to 1/3 of the flux at which electronic circuits begin to fail. Estimated increases in lifetimes by using a 3 x 50 orbit instead of a 3 x 3 orbit, and going from 1 to 2 g/sq cm are given.

  18. Investigation of solar wind and magnetospheric forcing effects on the outer Van Allen belt through multi-point measurements in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Daglis, I. A.; Katsavrias, C.; Georgiou, M.; Turner, D. L.; Sandberg, I.; Balasis, G.; Papadimitriou, K.

    2014-12-01

    We have investigated the response of the outer Van Allen belt electrons to various types of solar wind and internal magnetospheric forcing - in particular to Interplanetary Coronal Mass Ejections (ICMEs), to geospace magnetic storms of different intensities and to intense magnetospheric substorms. We have employed multi-point particle and field observations in the inner magnetosphere (both in-situ and through ground-based remote sensing), including the Cluster, THEMIS, Van Allen Probes and GOES constellations, the XMM and INTEGRAL spacecraft, and the CARISMA and IMAGE ground magnetometer arrays. The data provide a broad range of particle energies and a wide radial and azimuthal spatial coverage. This work has received support from the European Union's Seventh Framework Programme (FP7-SPACE-2011-1) under grant agreement no. 284520 for the MAARBLE (Monitoring, Analysing and Assessing Radiation Belt Energization and Loss) collaborative research project.

  19. Intense low-frequency chorus waves observed by Van Allen Probes: Fine structures and potential effect on radiation belt electrons

    NASA Astrophysics Data System (ADS)

    Gao, Zhonglei; Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zheng, Huinan; Wang, Yuming; Shen, Chao; Wang, Shui

    2016-02-01

    Frequency distribution is a vital factor in determining the contribution of whistler mode chorus to radiation belt electron dynamics. Chorus is usually considered to occur in the frequency range 0.1-0.8fce_eq (with the equatorial electron gyrofrequency fce_eq). We here report an event of intense low-frequency chorus with nearly half of wave power distributed below 0.1fce_eq observed by Van Allen Probe A on 27 August 2014. This emission propagated quasi-parallel to the magnetic field and exhibited hiss-like signatures most of the time. The low-frequency chorus can produce the rapid loss of low-energy (˜0.1 MeV) electrons, different from the normal chorus. For high-energy (≥0.5 MeV) electrons, the low-frequency chorus can yield comparable momentum diffusion to that of the normal chorus but much stronger (up to 2 orders of magnitude) pitch angle diffusion near the loss cone.

  20. On the Control of Van Allen Radiation Belt Morphology by Coupling to the Plasmasheet: How Quickly, How Deeply, and How Strongly?

    NASA Astrophysics Data System (ADS)

    Mann, Ian; Ozeke, Louis

    2016-07-01

    Here we examine the speed, strength and depth of the coupling between dynamical variations of the electron flux at the outer boundary and that in the heart of the radiation belts. Using ULF wave radial diffusion as an exemplar, we show how changing boundary conditions can completely change belt morphology even under conditions of identical wave power. In the case of ULF wave radial diffusion, whether there is a new source population or a sink of electron flux at the outer plasmasheet boundary can generate a completely opposite response which reaches deep into the belt even under identical ULF wave conditions. Very significantly, here we show that such coupling can occur on timescales much faster than previously thought, being as short as one hour or less between the outer boundary and L-shells in the heart of the belts at L˜4 and significantly less than the L-shell revisit time obtained from elliptically orbiting satellites such as the Van Allen Probes. We underline the importance of such boundary condition effects when seeking to identify the physical processes which explain the dominant behaviour of the Van Allen belts. We further examine implications for reaching science closure in identifying causality in radiation belt wave-particle dynamics, and in relation to observational requirements for accurate radiation belt forecasting. Overall we argue in general that the importance of boundary conditions is sometimes overlooked in comparison to the pursuit of (ever) increasingly accurate estimates of wave power and other wave properties used in empirical representations of wave transport and diffusion rates.

  1. Explaining the "Impenetrable Barrier" to Ultra-relativistic Electrons in the Van Allen Belts

    NASA Astrophysics Data System (ADS)

    Mann, I. R.; Ozeke, L.; Murphy, K. R.; Claudepierre, S. G.; Rae, J.; Milling, D. K.

    2015-12-01

    In recent observations, Baker et al. (Nature, 2014) reported the observation of an "impenetrable barrier" to the inner edge of the ultra-relativistic electron radiation belt. These authors demonstrated that this barrier location was not co-incident with the location of the plasmapause nor any other identifiable magnetospheric boundary; nor could it be explained by spatial structure resulting from the impacts of ground-based VLF transmitters. Here we show how the location of the "impenetrable barrier" can be explained as the location where there is a balance between inwards ULF wave radial diffusion and loss from lower band chorus and/or plasmaspheric hiss. Using recently derived data-driven ULF wave radial diffusion rates based on observations of ground-based ULF wave power characterised upto Kp=9 we can estimate the inward transport rates across a wide range of extreme activity levels. Contrary to the suggestion by Baker et al., there does not appear to be any need for active local wave particle acceleration between the plasmapause and the edge of the barrier at L*~2.8 since the radial diffusion rates appear to be sufficient to transport particles there during the most active times. The "impenetrable barrier" is explained as being defining as the locus where the rate of drift averaged loss matches the rate of inwards ULF wave radial diffusion. During more active times the location where loss is dominant moves inwards but reaches a limit of closest approach at L*~2.8 during the most active geomagnetic conditions (except during very short exceptional periods where interplanetary shocks and other shorter timescale processes can cause temporary filling of the slot). Overall, the "impenetrable barrier" is explained as a simple and natural consequence of the activity-dependent rates of ULF wave transport balanced by slow wave-particle scattering losses to the atmosphere closer to the Earth.

  2. NASA's Van Allen Probes RBSP-ECT Data Products and Access to Them: An Insider's Outlook on the Inner and Outer Belts (and We Don't Mean the Nation's Beltway...)

    NASA Astrophysics Data System (ADS)

    Smith, S. S.; Friedel, R. H. W.; Henderson, M. G.; Larsen, B.; Reeves, G. D.; Spence, H. E.

    2014-12-01

    In this poster, we present a summary of access to the data products of the Radiation Belt Storm Probes - Energetic Particle Composition, and Thermal plasma (RBSP-ECT) suite of NASA's Van Allen Probes mission. The RBSP-ECT science investigation (http://rbsp-ect.sr.unh.edu) measures comprehensively the near-Earth charged particle environment in order to understand the processes that control the acceleration, global distribution, and variability of radiation belt electrons and ions. RBSP-ECT data products derive from the three instrument elements that comprise the suite, which collectively covers the broad energies that define the source and seed populations, the core radiation belts, and also their highest energy ultra-relativistic extensions. These RBSP-ECT instruments include, from lowest to highest energies: the Helium, Oxygen, Proton, and Electron (HOPE) sensor, the Magnetic Electron and Ion Spectrometer (MagEIS), and the Relativistic Electron and Proton Telescope (REPT). We provide a brief overview of their principles of operation, as well as a description of the Level 1-3 data products that the HOPE, MagEIS, and REPT instruments produce, both separately and together. We provide a summary of how to access these RBSP-ECT data products at our Science Operation Center and Science Data Center (http://www.rbsp-ect.lanl.gov/rbsp_ect.php ) as well as caveats for their use. Finally, in the spirit of efficiently and effectively promoting and encouraging new collaborations, we present a summary of past publications, current studies, and opportunities for your future participation in RBSP-ECT science analyses.

  3. Diffusion of radiation belt protons by whistler waves

    NASA Astrophysics Data System (ADS)

    Villalon, Elena; Burke, William J.

    1994-11-01

    Whistler waves propagating near the quasi-electrostatic limit can interact with energetic protons (approximately 80 - 500 keV) that are transported into the radiation belts. The waves may be launched from either the ground or generated in the magnetosphere as a result of the resonant interactions with trapped electrons. The wave frequencies are significant fractions of the equatorial electron gyrofrequency, and they propagate obliquely to the geomagnetic field. A finite spectrum of waves compensates for the inhomogeneity of the geomagnetic field allowing the protons to stay in gyroresonance with the waves over long distances along magnetic field lines. The Fokker-Planck equation is intergrated along the flux tube considering the contributions of multiple-resonance crossings. The quasi-linear diffusion coefficients in energy, cross energy/ pitch angle, and pitch angle are obtained for second-order resonant interactions. They are sown to be proportional to the electric fields amplitudes. Numerical calculations for the second-order interactions show that diffusion dominates near the edge of the loss cone. For small pitch angles the largest diffusion coefficient is in energy, although the cross energy/ pitch angle term is also important. This may explain the induced proton precipitation observed in active space experiments.

  4. Field-Aligned Electron Events Observed in the Radiation Belts by the HOPE Instruments aboard the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Lejosne, S.; Agapitov, O. V.; Mozer, F.

    2015-12-01

    Field-aligned electron events (FAEs) are defined as events having the ratio of field-aligned to perpendicular flux greater than three. Time Domain Structures (TDS) are known to produce FAEs. Whistler and ECH waves are other possible candidates. Our objective is to derive the general features of the FAEs, to identify their driving mechanisms and to evaluate the importance of the different mechanisms. More than two years of measurements by the Helium Oxygen Proton Electron mass spectrometer and the Electric Field and Waves experiment are analyzed to identify low-energy (100eV-50keV) FAEs and to quantify the concurrent electric and magnetic wave components. We also peek at the observable waveforms with bursts of high-time resolution measurements. From statistical analysis and case studies, we suggest in particular that TDS cause field-alignment of ~300eV electrons in the pre-midnight sector while chorus waves cause field-alignment of electrons of ~10keV in the morning sector of the outer belt.

  5. Upcoming observations of whistler-mode waves in the outer Van Allen belt: multicomponent wave analyzer ELMAVAN for the Resonance mission

    NASA Astrophysics Data System (ADS)

    Santolik, Ondrej; Korepanov, Valery; Chugunin, Dmitriy; Kolmasova, Ivana; Uhlir, Ludek; Pronenko, Vira; Mogilevsky, Mikhail; Lan, Radek; Boychev, Boycho

    The instrument ELMAVAN is being prepared at the Institute of Atmospheric Physics, Prague in the frame of the Russian Resonance project with international participation. The aim of this four-spacecraft mission is to investigate properties of wave-particle interactions and plasma dynamics in the inner magnetosphere of the Earth with the focus on phenomena occurring within the same flux tube of the Earth's magnetic field. The wave emissions attract increasing attention because of their influence on the dynamics of the Earth’s radiation belts. The Resonance project therefore represents an excellent opportunity for the magnetospheric research, and together with the recently launched two-spacecraft US mission Van Allen Probes, it will contribute to our understanding of the Earth’s Van Allen radiation belts and the inner magnetosphere. ELMAVAN will measure intensity, polarization, coherence, and propagation properties of waves in magnetospheric plasmas. Three orthogonal magnetic search coil antennas and four electric monopoles will be used for the measurements. The instrument will measure fluctuations of the electric and magnetic field in the frequency range 10 Hz - 20 kHz. The scientific motivation is to investigate properties of whistler-mode chorus and hiss, and both equatorial and auroral emissions. Nonlinear wave-particle interactions will be the main target of these measurements. The input signals of ELMAVAN will consist of 3 analog signals from orthogonal magnetic search coil antennas and 4 analog signals from electric monopoles. The instrument ELMAVAN uses the state of the art electronics and mechanical design taking into account specific requirements for the orbit inside the radiation belts. From this point of view this instrument will also be important as a technological experiment. Engineering model of the analyzer was developed and tested in 2012-2013. Qualification model and the flight models are under preparation.

  6. A statistical study of proton pitch angle distributions measured by the Radiation Belt Storm Probes Ion Composition Experiment

    NASA Astrophysics Data System (ADS)

    Shi, Run; Summers, Danny; Ni, Binbin; Manweiler, Jerry W.; Mitchell, Donald G.; Lanzerotti, Louis J.

    2016-06-01

    A statistical study of ring current-energy proton pitch angle distributions (PADs) in Earth's inner magnetosphere is reported here. The data are from the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) on board the Van Allen Probe B spacecraft from 1 January 2013 to 15 April 2015. By fitting the data to the functional form sinnα, where α is the proton pitch angle, we examine proton PADs at the energies 50, 100, 180, 328, and 488 keV in the L shell range from L = 2.5 to L = 6. Three PAD types are classified: trapped (90° peaked), butterfly, and isotropic. The proton PAD dependence on the particle energy, magnetic local time (MLT), L shell, and geomagnetic activity are analyzed in detail. The results show a strong dependence of the proton PADs on MLT. On the nightside, the n values outside the plasmapause are clearly lower than those inside the plasmapause. At higher energies and during intense magnetic activity, nightside butterfly PADs can be observed at L shells down to the vicinity of the plasmapause. The averaged n values on the dayside are larger than on the nightside. A maximum of the averaged n values occurs around L = 4.5 in the postnoon sector (12-16 MLT). The averaged n values show a dawn-dusk asymmetry with lower values on the dawnside at high L shells, which is consistent with previous studies of butterfly PADs. The MLT dependence of the proton PADs becomes more distinct with increasing particle energy. These features suggest that drift shell splitting coupled with a radial flux gradient play an important role in the formation of PADs, particularly at L > ~ 4.5.

  7. Non-Resonant Scattering of Inner Belt Protons by Oblique Emic Waves from a Space-Borne Antenna

    NASA Astrophysics Data System (ADS)

    de Soria-Santacruz Pich, M.; Martinez-Sanchez, M.; Shprits, Y.

    2013-12-01

    The radiation of Electromagnetic Ion Cyclotron (EMIC) waves from a space-borne antenna has been proposed as a way to remediate the inner Van Allen proton belt. These energetic protons represent an obstacle to development of space technologies. Man-made EMIC waves, however, may induce pitch-angle scattering of the hazardous particles and precipitate them into the atmosphere, thus reducing the risk to spacecraft. EMIC waves from in-situ transmitters propagate mostly with perpendicular wave number vectors and field aligned group velocity. The spreading of these waves across field lines is therefore very small, i.e. the antenna illuminates a very narrow region of space that is confined along geomagnetic field lines. Additionally, the drift period of energetic protons is very fast, between 10 to 100 seconds at L=1.5 depending on their energy. Particles, therefore, drift through the illuminated region in a fraction of a second, where they are instantly scattered by the waves. The interaction time is more than one order of magnitude shorter than the proton gyroperiod, and occurs approximately once per particle drift orbit. In this study we analyze the nature of this interaction by solving the non-gyroaveraged equations of motion of energetic test protons interacting with man-made EMIC waves. The study shows that non-resonant wave-particle interactions dominate the scattering compared to resonant ones. Most theories on wave-particle interactions, like quasi-linear diffusion or the gyroaveraged approach, emphasize the resonant interaction but neglect the non-resonant effect. We show, however, that the latter is the dominant contribution to the scattering for wave-particle encounters shorter than a gyroperiod. From this non-gyroaveraged test particle solution, we next calculate the corresponding diffusion rates due to the non-resonant scattering. These diffusion rates are more than two orders of magnitude larger than the ones from quasi-linear theory or the gyroaveraged

  8. Middle atmosphere NO/x/ production due to ion propulsion induced radiation belt proton precipitation

    NASA Technical Reports Server (NTRS)

    Aikin, A. C.; Jackman, C. H.

    1980-01-01

    The suggestion that keV Ar(+) resulting from ion propulsion operations during solar power satellite construction could cause energetic proton precipitation from the inner radiation belt is examined to determine if such precipitation could cause significant increases in middle atmosphere nitric oxide concentrations thereby adversely affecting stratospheric ozone. It is found that the initial production rate of NO (mole/cu cm-sec) at 50 km is 130 times that due to nitrous oxide reacting with excited oxygen. However, since the time required to empty the inner belt of protons is about 1 sec and short compared to the replenishment time due to neutron decay, precipitation of inner radiation belt protons will have no adverse atmospheric environmental effect.

  9. Control of the energetic proton flux in the inner radiation belt by artificial means

    NASA Astrophysics Data System (ADS)

    Shao, X.; Papadopoulos, K.; Sharma, A. S.

    2009-07-01

    Earth's inner radiation belt located inside L = 2 is dominated by a relatively stable flux of trapped protons with energy from a few to over 100 MeV. Radiation effects in spacecraft electronics caused by the inner radiation belt protons are the major cause of performance anomalies and lifetime of Low Earth Orbit satellites. For electronic components with large feature size, of the order of a micron, anomalies occur mainly when crossing the South Atlantic Anomaly. However, current and future commercial electronic systems are incorporating components with submicron size features. Such systems cannot function in the presence of the trapped 30-100 MeV protons, as hardening against such high-energy protons is essentially impractical. The paper discusses the basic physics of the interaction of high-energy protons with low-frequency Shear Alfven Wave (SAW) under conditions prevailing in the radiation belts. Such waves are observed mainly in the outer belt, and it is believed that they are excited by an Alfven Ion Cyclotron instability driven by anisotropic equatorially trapped energetic protons. The paper derives the bounce and drift-averaged diffusion coefficients and uses them to determine the proton lifetime as a function of the spectrum and amplitude of the volume-averaged SAW resonant with the trapped energetic protons. The theory is applied to the outer and inner radiation belts. It is found that the resonant interaction of observed SAW with nT amplitude in the outer belt results in low flux of trapped protons by restricting their lifetime to periods shorter than days. A similar analysis for the inner radiation belt indicates that broadband SAW in the 1-10 Hz frequency range and average amplitude of 25 pT would reduce the trapped energetic proton flux by more than an order of magnitude within 2 to 3 years. In the absence of naturally occurring SAW waves, such reduction can be achieved by injecting such waves from ground-based transmitters. The analysis indicates

  10. Radial dependence of ionization losses of protons of the Earth's radiation belts

    NASA Astrophysics Data System (ADS)

    Kovtyukh, A. S.

    2016-01-01

    Coulomb losses and charge exchange of protons are considered in detail. On the basis of modern models of the plasmasphere and the exosphere, the radial dependences of the rates of ionization losses of protons, with μ from 0.3 to 10 keV nT-1, of the Earth's radiation belts near the equatorial plane are calculated for quiet periods. For calculation of Coulomb losses of protons we used data of ISEE-1 satellite (protons with energy from 24 to 2081 keV) on L from 3 to 9, data of Explorer-45 satellite (protons with energy from 78.6 to 872 keV) on L from 3 to 5 and data of CRRES satellite (protons with energy from 1 to 100 MeV) on L ≤ 3 (L is the McIlwain parameter). It is shown that with decreasing L the rate of ionization losses of protons of the radiation belts is reduced; for protons with μ > 1.2 keV nT-1 in a narrow region (ΔL ˜ 0.5) in the district of plasmapause in this dependence may form a local minimum of the rate. We found that the dependence from μ of the boundary on L between Coulomb losses and charge exchange of the trapped protons with hydrogen atoms is well approximated by the function Lb = 4.71μ0.32, where [μ] = keV nT-1. Coulomb losses dominate at L < Lb(μ), and at L > Lb(μ) dominates charge exchange of protons. We found the effect of subtracting the Coulomb losses from the charge exchange of protons of the radiation belts at low μ and L, which can simulate a local source of particles.

  11. Proton whistler interactions near the equator in the radiation belts

    NASA Astrophysics Data System (ADS)

    Villalon, Elena; Burke, William J.

    1993-08-01

    The interactions of energetic protons with whistlers propagating near the quasi-electrostatic limit are investigated using a test-particle Hamiltonian formalism. Near the equator the protons interact with the waves which appear Doppler-shifted to some harmonic of their cyclotron frequency. In an inhomogeneous geomagnetic field the spacing between cyclotron harmonic resonances is very small. The Hamiltonian equations of motion are solved including multiple independent harmonics for each resonance. The wave frequency varies as a function of the distance along the field line, with only one frequency being resonant at a given point. Thus the inhomogeneity of the magnetic field is compensated by the frequency variation. The proton whistler interactions satisfy the conditions for second-order resonances for all the harmonics. The resonances may also overlap in phase space, leading to significant changes in the protons energies and pitch angles. The combined contributions of positive and negative harmonics allow protons to diffuse toward smaller pitch angles. Numerical calculations applying this formalism to parameters relevant to the plasmasphere and controlled VLF transmission experiments are presented.

  12. Simulation of proton radiation belt formation during the March 24, 1991 SSC

    NASA Technical Reports Server (NTRS)

    Hudson, M. K.; Kotelnikov, A. D.; Li, X.; Roth, I.; Temerin, M.; Wygant, J.; Blake, J. B.; Gussenhoven, M. S.

    1995-01-01

    The rapid formation of a new proton radiation belt at L approximately = 2.5 following the March 24, 1991 Storm Sudden Commencement (SSC) observed at the Combined Release and Radiation Effects Satellite (CRRES) satellite is modeled using a relativistic guiding center test particle code. The SSC is modeled by a bipolar electric field and associated compression and relaxation in the magnetic field, superimposed on a dipole magnetic field. The source population consists of both solar and trapped inner zone protons. The simulations show that while both populations contribute to drift echoes in the 20-80 MeV range, primary conditions is from the solar protons. Proton acceleration by the SSC differs from relativistic electron acceleration in that different source populations contribute and nonrelativistic conservation of the first adiabatic invariation leads to greater energization of protons for a given decrease in L. Model drift echoes and flux distribution in L at the time of injection compare well with CRRES observations.

  13. Typical values of the electric drift E × B/B2 in the inner radiation belt and slot region as determined from Van Allen Probe measurements

    NASA Astrophysics Data System (ADS)

    Lejosne, Solène; Mozer, F. S.

    2016-12-01

    The electric drift E × B/B2 plays a fundamental role for the description of plasma flow and particle acceleration. Yet it is not well-known in the inner belt and slot region because of a lack of reliable in situ measurements. In this article, we present an analysis of the electric drifts measured below L 3 by both Van Allen Probes A and B from September 2012 to December 2014. The objective is to determine the typical components of the equatorial electric drift in both radial and azimuthal directions. The dependences of the components on radial distance, magnetic local time, and geographic longitude are examined. The results from Van Allen Probe A agree with Van Allen Probe B. They show, among other things, a typical corotation lag of the order of 5 to 10% below L 2.6, as well as a slight radial transport of the order of 20 m s-1. The magnetic local time dependence of the electric drift is consistent with that of the ionosphere wind dynamo below L 2 and with that of a solar wind-driven convection electric field above L 2. A secondary longitudinal dependence of the electric field is also found. Therefore, this work also demonstrates that the instruments on board Van Allen Probes are able to perform accurate measurements of the electric drift below L 3.

  14. Inferring electromagnetic ion cyclotron wave intensity from low altitude POES proton flux measurements: A detailed case study with conjugate Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Shi, Run; Ni, Binbin; Gu, Xudong; Zhang, Xianguo; Zuo, Pingbing; Fu, Song; Xiang, Zheng; Wang, Qi; Cao, Xing; Zou, Zhengyang

    2017-03-01

    Electromagnetic ion cyclotron (EMIC) waves play an important role in the magnetospheric particle dynamics and can lead to resonant pitch-angle scattering and ultimate precipitation of ring current protons. Commonly, the statistics of in situ EMIC wave measurements is adopted for quantitative investigation of wave-particle interaction processes, which however becomes questionable for detailed case studies especially during geomagnetic storms and substorms. Here we establish a novel technique to infer EMIC wave amplitudes from low-altitude proton measurements onboard the Polar Operational Environmental Satellites (POES). The detailed procedure is elaborated regarding how to infer the EMIC wave intensity for one specific time point. We then test the technique with a case study comparing the inferred root-mean-square (RMS) EMIC wave amplitude with the conjugate Van Allen Probes EMFISIS wave measurements. Our results suggest that the developed technique can reasonably estimate EMIC wave intensities from low-altitude POES proton flux data, thereby providing a useful tool to construct a data-based, near-real-time, dynamic model of the global distribution of EMIC waves once the proton flux measurements from multiple POES satellites are available for any specific time period.

  15. Effect of Thermospheric Neutral Density upon Inner Trapped-belt Proton Flux

    NASA Technical Reports Server (NTRS)

    Wilson, Thomas L.; Lodhi, M. A. K.; Diaz, Abel B.

    2007-01-01

    We wish to point out that a secular change in the Earth's atmospheric neutral density alters charged-particle lifetime in the inner trapped radiation belts, in addition to the changes recently reported as produced by greenhouse gases. Heretofore, changes in neutral density have been of interest primarily because of their effect on the orbital drag of satellites. We extend this to include the orbital lifetime of charged particles in the lower radiation belts. It is known that the charged-belt population is coupled to the neutral density of the atmosphere through changes induced by solar activity, an effect produced by multiple scattering off neutral and ionized atoms along with ionization loss in the thermosphere where charged and neutral populations interact. It will be shown here that trapped-belt flux J is bivariant in energy E and thermospheric neutral density , as J(E,rho). One can conclude that proton lifetimes in these belts are also directly affected by secular changes in the neutral species populating the Earth s thermosphere. This result is a consequence of an intrinsic property of charged-particle flux, that flux is not merely a function of E but is dependent upon density rho when a background of neutrals is present.

  16. Degradation of Akebono solar cell panels and variation of proton radiation belt

    NASA Astrophysics Data System (ADS)

    Ishikawa, H.; Miyake, W.; Matsuoka, A.

    2011-12-01

    We analyze long-term variation of electric current generated by Akebono solar cell panels (SCPI) and investigate how solar cell panels have been affected by space radiation. SCPI decreased slowly to about 7A in 2009 from 13A in 1989. The long-term decrease is probably due to various space radiations (Total Dose Effect). Therefore, we compare the decrease of solar cell output with solar proton flux measured by GOES satellites on GEO and with flux of trapped radiation from NASA's models (AP8 and AE8). We find a fair correlation between the decrease rate of solar cell output and trapped proton flux (above 10MeV) from the radiation model. However, we also find a few intervals of poor correlation, for an example, after a large geomagnetic storm occurred in March 1991, which suggests that stable proton radiation belt can be changed drastically for some special occasions.

  17. Source and loss processes of protons of the inner radiation belt.

    NASA Technical Reports Server (NTRS)

    Farley, T. A.; Walt, M.

    1971-01-01

    The adequacy of the known source and loss processes to populate the inner radiation belt with protons is examined by calculating the equilibrium trapped-proton distribution, which would result from decay of albedo neutrons, energy-loss collisions, and radial diffusion by changes in the third adiabatic invariant. The strength of the neutron source and the rates of atmospheric energy loss are obtained from available theoretical and experimental data, and the radial-diffusion coefficient is adjusted to give agreement between theory and experiment for equatorially trapped protons with first invariants between 200 and 3000 MeV gauss. The flux intensities, energy spectrums, and radial distributions obtained by the theory are in good agreement with observations, and the radial diffusion coefficient required is consistent with dif*usion coefficients derived by a variety of other methods.-

  18. HEO and CORONAS-F Electron and Proton Radiation Belt Data Comparison

    NASA Astrophysics Data System (ADS)

    Crosby, N.; Kuznetsov, S.; Fennell, J.; Heynderickx, D.; Myagkova, I.; Yushkov, B.

    World-wide attention was focussed on the October and November 2003 solar events due to the majestic nature of both the solar flares and the coronal mass ejections that were involved. These events especially caused technical problems for various spacecraft in geostationary orbit due to the fact that very large enhancements of energetic particles in the Earth's radiation belts occurred as an aftermath of the solar disturbances. To better understand how these solar events influenced the radiation belts it is important to compare radiation belt observations performed at different energies and locations in space. Here we present a comparison between observations performed by the HEO 1997-068 (HEO-3) spacecraft that has a highly elliptical orbit with an ˜67^o inclination and the CORONAS-F satellite with a circular high inclination (˜83^o) orbit with an altitude of 500 km. The HEO and CORONAS-F spacecraft provide both electron and proton radiation belt data in comparable energy ranges. Solar wind parameters and geomagnetic indices are also used in this study.

  19. Simplified Solar Modulation Model of Inner Trapped Belt Proton Flux As a Function of Atmospheric Density

    NASA Technical Reports Server (NTRS)

    Wilson, Thomas L.; Lodhi, M. A. K.; Diaz, Abel B.

    2005-01-01

    No simple algorithm seems to exist for calculating proton fluxes and lifetimes in the Earth's inner, trapped radiation belt throughout the solar cycle. Most models of the inner trapped belt in use depend upon AP8 which only describes the radiation environment at solar maximum and solar minimum in Cycle 20. One exception is NOAAPRO which incorporates flight data from the TIROS/NOAA polar orbiting spacecraft. The present study discloses yet another, simple formulation for approximating proton fluxes at any time in a given solar cycle, in particular between solar maximum and solar minimum. It is derived from AP8 using a regression algorithm technique from nuclear physics. From flux and its time integral fluence, one can then approximate dose rate and its time integral dose. It has already been published in this journal that the absorbed dose rate, D, in the trapped belts exhibits a power law relationship, D = A(rho)(sup -n), where A is a constant, rho is the atmospheric density, and the index n is weakly dependent upon shielding. However, that method does not work for flux and fluence. Instead, we extend this idea by showing that the power law approximation for flux J is actually bivariant in energy E as well as density rho. The resulting relation is J(E,rho)approx.(sum of)A(E(sup n))rho(sup -n), with A itself a power law in E. This provides another method for calculating approximate proton flux and lifetime at any time in the solar cycle. These in turn can be used to predict the associated dose and dose rate.

  20. Shielding of manned space vehicles against protons and alpha particles

    NASA Technical Reports Server (NTRS)

    Alsmiller, R. G., Jr.; Santoro, R. T.; Barish, J.; Claiborne, H. C.

    1972-01-01

    The available information on the shielding of manned space vehicles against protons and alpha particles is summarized. The emphasis is placed on shielding against Van Allen belt protons and against solar-flare protons and alpha particles, but information on shielding against galactic cosmic rays is also presented. The approximation methods for use by nonexperts in the space shielding field are those that are standard in the space shielding literature.

  1. Decay rate of the second radiation belt.

    PubMed

    Badhwar, G D; Robbins, D E

    1996-01-01

    Variations in the Earth's trapped (Van Allen) belts produced by solar flare particle events are not well understood. Few observations of increases in particle populations have been reported. This is particularly true for effects in low Earth orbit, where manned spaceflights are conducted. This paper reports the existence of a second proton belt and it's subsequent decay as measured by a tissue-equivalent proportional counter and a particle spectrometer on five Space Shuttle flights covering an eighteen-month period. The creation of this second belt is attributed to the injection of particles from a solar particle event which occurred at 2246 UT, March 22, 1991. Comparisons with observations onboard the Russian Mir space station and other unmanned satellites are made. Shuttle measurements and data from other spacecraft are used to determine that the e-folding time of the peak of the second proton belt. It was ten months. Proton populations in the second belt returned to values of quiescent times within eighteen months. The increase in absorbed dose attributed to protons in the second belt was approximately 20%. Passive dosimeter measurements were in good agreement with this value.

  2. Decay rate of the second radiation belt

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Robbins, D. E.

    1996-01-01

    Variations in the Earth's trapped (Van Allen) belts produced by solar flare particle events are not well understood. Few observations of increases in particle populations have been reported. This is particularly true for effects in low Earth orbit, where manned spaceflights are conducted. This paper reports the existence of a second proton belt and it's subsequent decay as measured by a tissue-equivalent proportional counter and a particle spectrometer on five Space Shuttle flights covering an eighteen-month period. The creation of this second belt is attributed to the injection of particles from a solar particle event which occurred at 2246 UT, March 22, 1991. Comparisons with observations onboard the Russian Mir space station and other unmanned satellites are made. Shuttle measurements and data from other spacecraft are used to determine that the e-folding time of the peak of the second proton belt. It was ten months. Proton populations in the second belt returned to values of quiescent times within eighteen months. The increase in absorbed dose attributed to protons in the second belt was approximately 20%. Passive dosimeter measurements were in good agreement with this value.

  3. Science Highlights from the RBSP-ECT Particle Instrument Suite on NASA's Van Allen Probes Mission

    NASA Astrophysics Data System (ADS)

    Spence, Harlan

    2014-05-01

    The NASA Van Allen Probes mission includes an instrument suite known as the Radiation Belt Storm Probes (RBSP) - Energetic Particle, Composition, and Thermal Plasma (ECT) suite. RBSP-ECT contains a well-proven complement of particle instruments to ensure the highest quality measurements ever made in the radiation belts and the inner magnetosphere. The coordinated RBSP-ECT particle measurements, analyzed in combination with fields and waves observations and state of-the-art theory and modeling, provide new understanding on the acceleration, global distribution, and variability of radiation belt electrons and ions, key science objectives of NASA's Living With a Star program and the Van Allen Probes mission. The RBSP-ECT suite consists of three highly-coordinated instruments: the Helium Oxygen Proton Electron (HOPE) spectrometer, the Magnetic Electron Ion Spectrometer (MagEIS), and the Relativistic Electron Proton Telescope (REPT). Collectively these three instrument types cover comprehensively the full electron and ion spectra from one eV to 10's of MeV with sufficient energy resolution, pitch angle coverage and resolution, and with composition measurements in the critical energy range up to 50 keV and also from a few to 50 MeV/nucleon. All three instruments are based on measurement techniques proven in the radiation belts, then optimized to provide unambiguous separation of ions and electrons and clean energy responses even in the presence of extreme penetrating background environments. In this presentation, we summarize overall ECT science goals and then show scientific results derived from the ECT suite on the dual Van Allen Probes spacecraft to date. Mission operations began only in late October 2012, and we have now achieved significant results. Results presented here will include substantial progress toward resolving primary Van Allen Probes science targets, such as: the relative role of localized acceleration versus transport-generated particle acceleration

  4. The Radiation Belt Storm Probes

    NASA Video Gallery

    The Radiation Belt Storm Probe mission (RBSP) will explore the Van Allen Radiation Belts in the Earth's magnetosphere. The charge particles in these regions can be hazardous to both spacecraft and ...

  5. Wave-wave and wave-particle interactions in the inner magnetosphere measured with Van Allen Probes: cross coupling between wave modes and its effect on radiation belt dynamics

    NASA Astrophysics Data System (ADS)

    Colpitts, C. A.; Cattell, C. A.; Broughton, M.; Engebretson, M. J.

    2015-12-01

    We will show observations of waveform bursts using the Electric Field and Waves (EFW) burst data on the Van Allen Probes satellites with intermediate frequency waves such as whistler mode, magnetosonic and lower hybrid. These observations show very strong modulation of these waves by lower frequency waves such as EMIC or ULF. We are analyzing the burst data and cross coupling between wave modes to determine how prevalent the cross coupling between wave modes is and under what conditions it occurs. To supplement the EFW data, each satellite is also equipped with a full complement of particle instruments, including the HOPE instrument measuring lower energy (1 eV - 50 keV) particles and MagEIS instruments measuring higher energy (20 keV - 5 MeV) particles. The energy and angular resolution of these detectors are sufficient to resolve the scattering and energization arising from the distinct wave modes, using the signatures in the trapped electron populations predicted by theory for the various mechanisms. Comparison of the burst waveform data with the electron data from HOPE and MagEIS, for times with and without coupling between the wave modes, will allow us to identify how the cross coupling affects electron dynamics in the radiation belts. The significance of wave-particle interactions in the formation and depletion of the radiation belts has long been established, but is still not completely understood. Specifically, pitch angle scattering from waves such as plasmaspheric hiss and electromagnetic ion cyclotron [EMIC] waves near the duskside plasmapause is known to contribute to electron loss from the radiation belts, primarily through precipitation into the atmosphere. Higher frequency waves such as whistler mode chorus and magnetosonic waves observed near the equator in the lower hybrid frequency range are widely believed to be primary means for electron energization. However, these and other competing processes often occur simultaneously, and an accurate model

  6. Three dimensional data-assimilative VERB-code simulations of the Earth's radiation belts: Reanalysis during the Van Allen Probe era, and operational forecasting

    NASA Astrophysics Data System (ADS)

    Kellerman, Adam; Shprits, Yuri; Podladchikova, Tatiana; Kondrashov, Dmitri

    2016-04-01

    The Versatile Electron Radiation Belt (VERB) code 2.0 models the dynamics of radiation-belt electron phase space density (PSD) in Earth's magnetosphere. Recently, a data-assimilative version of this code has been developed, which utilizes a split-operator Kalman-filtering approach to solve for electron PSD in terms of adiabatic invariants. A new dataset based on the TS07d magnetic field model is presented, which may be utilized for analysis of past geomagnetic storms, and for initial and boundary conditions in running simulations. Further, a data-assimilative forecast model is introduced, which has the capability to forecast electron PSD several days into the future, given a forecast Kp index. The model assimilates an empirical model capable of forecasting the conditions at geosynchronous orbit. The model currently runs in real time and a forecast is available to view online http://rbm.epss.ucla.edu.

  7. Modeling the Earth's radiation belts. A review of quantitative data based electron and proton models

    NASA Technical Reports Server (NTRS)

    Vette, J. I.; Teague, M. J.; Sawyer, D. M.; Chan, K. W.

    1979-01-01

    The evolution of quantitative models of the trapped radiation belts is traced to show how the knowledge of the various features has developed, or been clarified, by performing the required analysis and synthesis. The Starfish electron injection introduced problems in the time behavior of the inner zone, but this residue decayed away, and a good model of this depletion now exists. The outer zone electrons were handled statistically by a log normal distribution such that above 5 Earth radii there are no long term changes over the solar cycle. The transition region between the two zones presents the most difficulty, therefore the behavior of individual substorms as well as long term changes must be studied. The latest corrections to the electron environment based on new data are outlined. The proton models have evolved to the point where the solar cycle effect at low altitudes is included. Trends for new models are discussed; the feasibility of predicting substorm injections and solar wind high-speed streams make the modeling of individual events a topical activity.

  8. The proton and electron radiation belts at geosynchronous orbit: Statistics and behavior during high-speed stream-driven storms

    NASA Astrophysics Data System (ADS)

    Borovsky, Joseph E.; Cayton, Thomas E.; Denton, Michael H.; Belian, Richard D.; Christensen, Roderick A.; Ingraham, J. Charles

    2016-06-01

    The outer proton radiation belt (OPRB) and outer electron radiation belt (OERB) at geosynchronous orbit are investigated using a reanalysis of the LANL CPA (Charged Particle Analyzer) 8-satellite 2-solar cycle energetic particle data set from 1976 to 1995. Statistics of the OPRB and the OERB are calculated, including local time and solar cycle trends. The number density of the OPRB is about 10 times higher than the OERB, but the 1 MeV proton flux is about 1000 times less than the 1 MeV electron flux because the proton energy spectrum is softer than the electron spectrum. Using a collection of 94 high-speed stream-driven storms in 1976-1995, the storm time evolutions of the OPRB and OERB are studied via superposed epoch analysis. The evolution of the OERB shows the familiar sequence (1) prestorm decay of density and flux, (2) early-storm dropout of density and flux, (3) sudden recovery of density, and (4) steady storm time heating to high fluxes. The evolution of the OPRB shows a sudden enhancement of density and flux early in the storm. The absence of a proton dropout when there is an electron dropout is noted. The sudden recovery of the density of the OERB and the sudden density enhancement of the OPRB are both associated with the occurrence of a substorm during the early stage of the storm when the superdense plasma sheet produces a "strong stretching phase" of the storm. These storm time substorms are seen to inject electrons to 1 MeV and protons to beyond 1 MeV into geosynchronous orbit, directly producing a suddenly enhanced radiation belt population.

  9. A neural network approach for identifying particle pitch angle distributions in Van Allen Probes data

    NASA Astrophysics Data System (ADS)

    Souza, V. M.; Vieira, L. E. A.; Medeiros, C.; Da Silva, L. A.; Alves, L. R.; Koga, D.; Sibeck, D. G.; Walsh, B. M.; Kanekal, S. G.; Jauer, P. R.; Rockenbach, M.; Dal Lago, A.; Silveira, M. V. D.; Marchezi, J. P.; Mendes, O.; Gonzalez, W. D.; Baker, D. N.

    2016-04-01

    Analysis of particle pitch angle distributions (PADs) has been used as a means to comprehend a multitude of different physical mechanisms that lead to flux variations in the Van Allen belts and also to particle precipitation into the upper atmosphere. In this work we developed a neural network-based data clustering methodology that automatically identifies distinct PAD types in an unsupervised way using particle flux data. One can promptly identify and locate three well-known PAD types in both time and radial distance, namely, 90° peaked, butterfly, and flattop distributions. In order to illustrate the applicability of our methodology, we used relativistic electron flux data from the whole month of November 2014, acquired from the Relativistic Electron-Proton Telescope instrument on board the Van Allen Probes, but it is emphasized that our approach can also be used with multiplatform spacecraft data. Our PAD classification results are in reasonably good agreement with those obtained by standard statistical fitting algorithms. The proposed methodology has a potential use for Van Allen belt's monitoring.

  10. Survival of bacterial isolates exposed to simulated Jovian trapped radiation belt electrons and solar wind protons

    NASA Technical Reports Server (NTRS)

    Taylor, D. M.; Hagen, C. A.; Renninger, G. M.; Simko, G. J.; Smith, C. D.; Yelinek, J. A.

    1973-01-01

    With missions to Jupiter, the spacecraft will be exposed for extended durations to solar wind radiation and the Jovian trapped radiation belt. This study is designed to determine the effect of these radiation environments on spacecraft bacterial isolates. The information can be used in the probability of contamination analysis for these missions. A bacterial subpopulation from Mariner Mars 1971 spacecraft (nine spore-forming and three non-spore-forming isolates) plus two comparative organisms, Staphylococcus epidermidis ATCC 17917 and a strain of Bacillus subtilis var. niger, were exposed to 2, 12, and 25 MeV electrons at different doses with simultaneous exposure to a vacuum of 1.3 x 10(-4) N m-2 at 20 and -20 degrees C. The radioresistance of the subpopulation was dependent on the isolate, dose and energy of electrons. Temperature affected the radioresistance of only the spore-forming isolates. Survival data indicated that spores were reduced approximately 1 log/1500 J kg-1 (10 J kg-1=1 krad), while non-spore-forming isolates (micrococci) were reduced 1.5-2 logs/1500 J kg-1 with the exception of an apparent radioresistant isolate whose resistance approached that of the spores. The subpopulation was found to be less resistant to lower energy than to higher energy electrons. The bacterial isolates were exposed to 3 keV protons under the same conditions as the electrons with a total fluence of 1.5 x 10(13) p cm-2 and a dose rate of 8.6 x 10(9) p cm-2 s-1. The results showed that only 20% of S. epidermidis and 45% of B. subtilis populations survived exposure to the 3 keV protons, while the mean survival of the spacecraft subpopulation was 45% with a range from 31.8% (non-spore-former) to 64.8% (non-spore-former). No significant difference existed between spore-forming and non-spore-forming isolates.

  11. Survival of bacterial isolates exposed to simulated Jovian trapped radiation belt electrons and solar wind protons.

    PubMed

    Taylor, D M; Hagen, C A; Renninger, G M; Simko, G J; Smith, C D; Yelinek, J A

    1973-01-01

    With missions to Jupiter, the spacecraft will be exposed for extended durations to solar wind radiation and the Jovian trapped radiation belt. This study is designed to determine the effect of these radiation environments on spacecraft bacterial isolates. The information can be used in the probability of contamination analysis for these missions. A bacterial subpopulation from Mariner Mars 1971 spacecraft (nine spore-forming and three non-spore-forming isolates) plus two comparative organisms, Staphylococcus epidermidis ATCC 17917 and a strain of Bacillus subtilis var. niger, were exposed to 2, 12, and 25 MeV electrons at different doses with simultaneous exposure to a vacuum of 1.3 x 10(-4) N m-2 at 20 and -20 degrees C. The radioresistance of the subpopulation was dependent on the isolate, dose and energy of electrons. Temperature affected the radioresistance of only the spore-forming isolates. Survival data indicated that spores were reduced approximately 1 log/1500 J kg-1 (10 J kg-1=1 krad), while non-spore-forming isolates (micrococci) were reduced 1.5-2 logs/1500 J kg-1 with the exception of an apparent radioresistant isolate whose resistance approached that of the spores. The subpopulation was found to be less resistant to lower energy than to higher energy electrons. The bacterial isolates were exposed to 3 keV protons under the same conditions as the electrons with a total fluence of 1.5 x 10(13) p cm-2 and a dose rate of 8.6 x 10(9) p cm-2 s-1. The results showed that only 20% of S. epidermidis and 45% of B. subtilis populations survived exposure to the 3 keV protons, while the mean survival of the spacecraft subpopulation was 45% with a range from 31.8% (non-spore-former) to 64.8% (non-spore-former). No significant difference existed between spore-forming and non-spore-forming isolates.

  12. Radiation Belt Storm Probe Mission Trailer

    NASA Video Gallery

    With launch scheduled for 2012, the Radiation Belt Storm Probe (RBSP) are two identical spacecraft that will investigate the doughnut shaped Van Allen radiation belts, the first discovery of the sp...

  13. Cross-scale observations of the 2015 St. Patrick's day storm: THEMIS, Van Allen Probes, and TWINS

    NASA Astrophysics Data System (ADS)

    Goldstein, J.; Angelopoulos, V.; De Pascuale, S.; Funsten, H. O.; Kurth, W. S.; LLera, K.; McComas, D. J.; Perez, J. D.; Reeves, G. D.; Spence, H. E.; Thaller, S. A.; Valek, P. W.; Wygant, J. R.

    2017-01-01

    We present cross-scale magnetospheric observations of the 17 March 2015 (St. Patrick's Day) storm, by Time History of Events and Macroscale Interactions during Substorms (THEMIS), Van Allen Probes (Radiation Belt Storm Probes), and Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS), plus upstream ACE/Wind solar wind data. THEMIS crossed the bow shock or magnetopause 22 times and observed the magnetospheric compression that initiated the storm. Empirical models reproduce these boundary locations within 0.7 RE. Van Allen Probes crossed the plasmapause 13 times; test particle simulations reproduce these encounters within 0.5 RE. Before the storm, Van Allen Probes measured quiet double-nose proton spectra in the region of corotating cold plasma. About 15 min after a 0605 UT dayside southward turning, Van Allen Probes captured the onset of inner magnetospheric convection, as a density decrease at the moving corotation-convection boundary (CCB) and a steep increase in ring current (RC) proton flux. During the first several hours of the storm, Van Allen Probes measured highly dynamic ion signatures (numerous injections and multiple spectral peaks). Sustained convection after ˜1200 UT initiated a major buildup of the midnight-sector ring current (measured by RBSP A), with much weaker duskside fluxes (measured by RBSP B, THEMIS a and THEMIS d). A close conjunction of THEMIS d, RBSP A, and TWINS 1 at 1631 UT shows good three-way agreement in the shapes of two-peak spectra from the center of the partial RC. A midstorm injection, observed by Van Allen Probes and TWINS at 1740 UT, brought in fresh ions with lower average energies (leading to globally less energetic spectra in precipitating ions) but increased the total pressure. The cross-scale measurements of 17 March 2015 contain significant spatial, spectral, and temporal structure.

  14. "Nonempty" Gap Between Radiation Belts: The First Observations

    NASA Astrophysics Data System (ADS)

    Panasyuk, Mikhail

    2013-12-01

    The first space experiments carried out in 1958 by the scientific groups of James Van Allen (United States) on board the first Explorer satellites and Sergey Vernov (Soviet Union) on board the satellite Sputnik 3 led to the discovery of the Earth's radiation belts—the particles (mainly protons and electrons) captured by the magnetic field of the Earth. Two scientific groups independently came to the conclusion that the electrons in the geomagnetic trapping region fill two areas, inner and outer radiation belts, unlike the protons, which fill the whole trapping region [see, e.g., Lemaire, 2000].

  15. A long-lived refilling event of the slot region between the Van Allen radiation belts from Nov 2004 to Jan 2005

    NASA Astrophysics Data System (ADS)

    Yang, X.

    2015-12-01

    A powerful relativistic electron enhancement in the slot region between the inner and outer radiation belts is investigated by multi-satellites measurements. The measurement from Space Particle Component Detectors (SPCDs) aboard Fengyun-1 indicates that the relativistic electron (>1.6MeV) flux began to enhance obviously on early 10 November with the flux peak fixed at L~3.0. In the next day, the relativistic electron populations increased dramatically. Subsequently, the flux had been enhancing slowly, but unceasingly, until 17 November, and the maximum flux reached up to 7.8×104 cm-2·sr-1·s-1 at last. The flux peak fixed at L~3.0 and the very slow decay rate in this event make it to be an unusual long-lived slot region refilling event. We trace the cause of the event back to the interplanetary environment and find that there were two evident magnetic cloud constructions: dramatically enhanced magnetic field strength and long and smooth rotation of field vector from late 7 to 8 November and from late 9 to 10 November, respectively; solar wind speed increased in 'step-like' fashion on late 7 November and persisted the level of high speed >560 km·s-1 for about 124 hours. Owed to the interplanetary disturbances, very strong magnetic storms and substorms occurred in the magnetosphere. Responding to the extraordinarily magnetic perturbations, the plasmasphere shrank sharply. The location of plasmapause inferred from Dst indicates that the plasmapause shrank inward to as low as L~2.5. On account of these magnetospheric conditions, strong chorus emissions are expected near the earth. In fact, the STAFF on Cluster mission measured intensive whistler mode chorus emissions on 10 and 12 November, corresponding to the period of the remarkable enhancement of relativistic electron. Furthermore, we investigate the radial profile of phase space density (PSD) by electron flux from multi-satellites, and the evolution of the phase space density profile reveals that the local

  16. Interaction of ring current and radiation belt protons with ducted plasmaspheric hiss. 2. Time evolution of the distribution function

    NASA Astrophysics Data System (ADS)

    Kozyra, J. U.; Rasmussen, C. E.; Miller, R. H.; Villalon, E.

    1995-11-01

    The evolution of the bounce-averaged ring current/radiation belt proton distribution is simulated during resonant interactions with ducted plasmaspheric hiss. The plasmaspheric hiss is assumed to be generated by ring current electrons and to be damped by the energetic protons. Thus energy is transferred between energetic electrons and protons using the plasmaspheric hiss as a mediary. The problem is not solved self-consistently. During the simulation period, interactions with ring current electrons (not represented in the model) are assumed to maintain the wave amplitudes in the presence of damping by the energetic protons, allowing the wave spectrum to be held fixed. Diffusion coefficients in pitch angle, cross pitch angle/energy, and energy were previously calculated by Kozyra et al. (1994) and are adopted for the present study. The simulation treats the energy range, E>=80 keV, within which the wave diffusion operates on a shorter timescale than other proton loss processes (i.e., Coulomb drag and charge exchange). These other loss processes are not included in the simulation. An interesting result of the simulation is that energy diffusion maximizes at moderate pitch angles near the edge of the atmospheric loss cone. Over the simulation period, diffusion in energy creates an order of magnitude enhancement in the bounce-averaged proton distribution function at moderate pitch angles. The loss cone is nearly empty because scattering of particles at small pitch angles is weak. The bounce-averaged flux distribution, mapped to ionospheric heights, results in elevated locally mirroring proton fluxes. OGO 5 observed order of magnitude enhancements in locally mirroring energetic protons at altitudes between 350 and 1300 km and invariant latitudes between 50° and 60° (Lundblad and Soraas, 1978). The proton distributions were highly anisotropic in pitch angle with nearly empty loss cones. The similarity between the observed distributions and those resulting from this

  17. Previously Undetected Radiation Belt Revealed

    NASA Video Gallery

    Since their discovery over 50 years ago, the Earth'€™s Van Allen radiation belts have been considered to consist of two distinct zones of trapped, highly energetic charged particles. Observations f...

  18. Upper limit on the inner radiation belt MeV electron intensity

    PubMed Central

    Li, X; Selesnick, RS; Baker, DN; Jaynes, AN; Kanekal, SG; Schiller, Q; Blum, L; Fennell, J; Blake, JB

    2015-01-01

    No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (tens of MeV to GeV). The inner belt proton flux level, however, is relatively stable; thus, for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment on board Colorado Student Space Weather Experiment CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because their flux level is orders of magnitude higher than the background, while higher-energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, quantified upper limits on MeV electron fluxes in various energy ranges in the inner belt. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about 1 order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, which have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt. Key Points Quantified upper limit of MeV electrons in the inner belt Actual MeV electron intensity likely much lower than the upper limit More detailed understanding of relativistic electrons in the magnetosphere PMID:26167446

  19. Recent Advances in Understanding Radiation Belt Dynamics in the Earth's Inner Zone and Slot Region

    NASA Astrophysics Data System (ADS)

    Li, X.

    2015-12-01

    Comprehensive measurements of the inner belt protons from the Relativistic Electron and Proton Telescope (REPT) onboard Van Allen Probes, in a geo-transfer-like orbit, revealed new features of inner belt protons in terms of their spectrum distribution, spatial distribution, pitch angle distribution, and their different source populations. Concurrent measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) on board Colorado Student Space Weather Experiment (CSSWE) CubeSat, in a highly inclined low Earth orbit, and REPT demonstrated that there exist sub-MeV electrons in the inner belt and their flux level is orders of magnitude higher than the background associated with the inner belt protons, while higher energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Analysis on sub-MeV electrons data in the inner belt and slot region from the Magnetic Electron Ion Spectrometer (MagEIS) on board Van Allen Probes revealed rather complicated pitch angle distribution of these energetic electrons, with the 90 deg-minimum (butterfly) pitch angle distribution dominating near the magnetic equator. Furthermore, it is clearly shown from MagEIS measurements that 10s - 100s keV electrons are commonly seen penetrating into the inner belt region during geomagnetic active times while protons of similar energies are hardly seen there. These are part of a summary of the most recent measurements and understanding of the dynamics of energetic particles in the inner zone and slot region to be exhibited and discussed in this presentation.

  20. Evolution of relativistic outer belt electrons during extended quiescent period

    NASA Astrophysics Data System (ADS)

    Jaynes, A. N.; Li, X.; Schiller, Q.; Blum, L. W.; Tu, W.; Malaspina, D.; Turner, D.; Baker, D. N.; Kanekal, S. G.; Blake, J. B.; Wygant, J. R.

    2013-12-01

    To effectively study loss due to precipitation of relativistic electron fluxes in the radiation belt, it is necessary to isolate this loss from the Dst effect and magnetopause shadowing by studying loss during a time of relatively quiet geomagnetic activity. We present a study of the slow decay of 200 keV - 2 MeV electron populations in the outer radiation belt during an extended quiescent period from ~15 Dec 2012 - 10 Jan 2013, wherein Dst never extended below -25 nT. We incorporate particle measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) onboard the Colorado Student Space Weather Experiment (CSSWE) CubeSat with measurements from the Relativistic Electron Proton Telescope (REPT) and the Magnetic Electron Ion Spectrometer (MagEIS) on the Van Allen Probes twin spacecraft to understand the evolution of the electron populations across pitch angle and energy. First, we present REPTile measurements of the precipitating populations (along with trapped & quasi-trapped) at a low-earth orbit, offering a view into the loss cone that is not as easily resolved using only the Van Allen Probes. Electron loss to the atmosphere during this event is quantified through use of a precipitation loss model, using the REPTile measurements. Additionally, phase space densities are derived using pitch-angle-resolved flux data from the REPT and MagEIS instruments, as well as from THEMIS SST data. Finally, we present the net loss effect on the outer radiation belt content during this time, by incorporating the modeled precipitation loss (from REPTile measurements) with Van Allen Probes electron flux data. Hiss and chorus wave data, along with approximate plasmapause location, from Van Allen Probes' Electric Field and Waves Suite (EFW) completes the picture by suggesting mechanisms for the precipitation loss of relativistic electrons during quiet time.

  1. Interaction of ring current and radiation belt protons with ducted plasmaspheric hiss. 1: Diffusion coefficients and timescales

    NASA Technical Reports Server (NTRS)

    Kozyra, J. U.; Rasmussen, C. E.; Miller, R. H.; Lyons, L. R.

    1994-01-01

    Protons that are convected into the inner magnetosphere in response to enhanced magnetic activity can resonate with ducted plasmaspheric hiss in the outer plasmasphere via an anomalous Doppler-shifted cyclotron resonance. Plasmaspheric hiss is a right-hand-polarized electromagnetic emission that is observed to fill the plasmasphere on a routine basis. When plasmaspheric hiss is confined within field-aligned ducts or guided along density gradients, wave normal angles remain largely below 45 deg. This allows resonant interactions with ions at typical ring current and radiation belt energies to take place. Such field-aligned ducts have been observed both within the plasmasphere and in regions outside of the plasmasphere. Wave intensities are estimated using statistical information from studies of detached plasma regions. Diffusion coefficients are presented for a range of L shells and proton energies for a fixed wave distribution. Harmonic resonances in the range N = +/-100 are considered in order to include interactions between hiss at 100 Hz to 2 kHz frequencies, and protons in the energy range between approximately 10 keV and 1000 keV. Diffusion timescales are estimated to be of the order of tens of days and comparable to or shorter than lifetimes for Coulomb decay and charge exchange losses over most of the energy and spatial ranges of interest.

  2. Deduction of the rates of radial diffusion of protons from the structure of the Earth's radiation belts

    NASA Astrophysics Data System (ADS)

    Kovtyukh, Alexander S.

    2016-11-01

    From the data on the fluxes and energy spectra of protons with an equatorial pitch angle of α0 ≈ 90° during quiet and slightly disturbed (Kp ≤ 2) periods, I directly calculated the value DLL, which is a measure of the rate of radial transport (diffusion) of trapped particles. This is done by successively solving the systems (chains) of integrodifferential equations which describe the balance of radial transport/acceleration and ionization losses of low-energy protons of the stationary belt. This was done for the first time. For these calculations, I used data of International Sun-Earth Explorer 1 (ISEE-1) for protons with an energy of 24 to 2081 keV at L = 2-10 and data of Explorer-45 for protons with an energy of 78.6 to 872 keV at L = 2-5. Ionization losses of protons (Coulomb losses and charge exchange) were calculated on the basis of modern models of the plasmasphere and the exosphere. It is shown that for protons with μ from ˜ 0.7 to ˜ 7 keV nT-1 at L ≈ 4.5-10, the functions of DLL can be approximated by the following equivalent expressions: DLL ≈ 4.9 × 10-14μ-4.1L8.2 or DLL ≈ 1.3 × 105(EL)-4.1 or DLL ≈ 1.2 × 10-9fd-4.1, where fd is the drift frequency of the protons (in mHz), DLL is measured in s-1, E is measured in kiloelectronvolt and μ is measured in kiloelectronvolt per nanotesla. These results are consistent with the radial diffusion of particles under the action of the electric field fluctuations (pulsations) in the range of Pc6 and contradict the mechanism of the radial diffusion of particles under the action of sudden impulses (SIs) of the magnetic field and also under the action of substorm impulses of the electric field. During magnetic storms DLL increases, and the expressions for DLL obtained here can change completely.

  3. Upper limit on the inner radiation belt MeV electron intensity.

    PubMed

    Li, X; Selesnick, R S; Baker, D N; Jaynes, A N; Kanekal, S G; Schiller, Q; Blum, L; Fennell, J; Blake, J B

    2015-02-01

    No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (tens of MeV to GeV). The inner belt proton flux level, however, is relatively stable; thus, for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment on board Colorado Student Space Weather Experiment CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because their flux level is orders of magnitude higher than the background, while higher-energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, quantified upper limits on MeV electron fluxes in various energy ranges in the inner belt. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about 1 order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, which have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt.

  4. New results from the Colorado CubeSat and comparison with Van Allen Probes data

    NASA Astrophysics Data System (ADS)

    Li, X.

    2013-05-01

    The Colorado Student Space Weather Experiment (CSSWE) is a 3-unit (10cm x 10cm x 30cm) CubeSat mission funded by the NSF, launched into a highly inclined (650) low-Earth (490km x 790km) orbit on 09/13/12 as a secondary payload under NASA's Educational Launch of Nanosatellites (ELaNa) program. CSSWE contains a single science payload, the Relativistic Electron and Proton Telescope integrated little experiment (REPTile), which is a simplified and miniaturized version of the Relativistic Electron and Proton Telescope (REPT) built at the Laboratory for Atmospheric and Space Physics (LASP) of University of Colorado for NASA/Van Allen Probes mission, which consists of two identical spacecraft, launched on 08/30/12, that traverse the heart of the radiation belts in a low inclination (100) orbit. REPTile is designed to measure the directional differential flux of protons ranging from 9 to 40 MeV and electrons from 0.5 to >3.3 MeV. Three-month science mission (full success) was completed on 1/05/13. We are now into the extended mission phase, focusing on data analysis and modeling. REPTile measures a fraction of the total population that has small enough equatorial pitch angles to reach the altitude of CSSWE, thus measuring the precipitating population as well as the trapped population. These measurements are critical for understanding the loss of outer radiation belt electrons. New results from CSSWE and comparison with Van Allen Probes data will be presented. The CSSWE is also an ideal class project, involving over 65 graduate and undergraduate students and providing training for the next generation of engineers and scientists over the full life-cycle of a satellite project.

  5. Ultra-fast Electrons Explain Third Radiation Belt

    NASA Video Gallery

    In September 2012, NASA's Van Allen Probes observed the radiation belts around Earth had settled into a new configuration, separating into three belts instead of two. Scientists think the unusual p...

  6. Peculiar pitch angle distribution of relativistic electrons in the inner radiation belt and slot region

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Blake, J. B.; Fennell, J. F.; Claudepierre, S. G.; Baker, D. N.; Jaynes, A. N.; Malaspina, D. M.; Kanekal, S. G.

    2014-04-01

    The relativistic electrons in the inner radiation belt have received little attention in the past due to sparse measurements and unforgiving contamination from the inner belt protons. The high-quality measurements of the Magnetic Electron Ion Spectrometer instrument onboard Van Allen Probes provide a great opportunity to investigate the dynamics of relativistic electrons in the low L region. In this letter, we report the newly unveiled pitch angle distribution (PAD) of the energetic electrons with minima at 90° near the magnetic equator in the inner belt and slot region. Such a PAD is persistently present throughout the inner belt and appears in the slot region during storms. One hypothesis for 90° minimum PADs is that off 90° electrons are preferentially heated by chorus waves just outside the plasmapause (which can be at very low L during storms) and/or fast magnetosonic waves which exist both inside and outside the plasmasphere.

  7. On spatial distribution of proton radiation belt from solar cell degradation of Akebono satellite

    NASA Astrophysics Data System (ADS)

    Miyake, W.; Miyoshi, Y.; Matsuoka, A.

    2013-12-01

    Solar cells on any satellite degrade gradually due to severe space radiation environment. We found a fair correlation between the decrease rate of solar cell output current of Akebono satellite orbiting in the inner magnetosphere and trapped proton flux from AP8 model between 1989 and 1992. After 1993, presumably as a result of long-term degradation, variation of solar cell output seems more susceptible to other causes such as high temperature effect, and simple monthly averaged data show no significant relation between them. One of possible causes for the temperature variation of the solar cells is terrestrial heat radiation with changing orientation of solar cell panels towards the earth and another is solar radiation varied with eccentric earth's orbit around the sun. In order to remove the possible temperature effect, we sort the data expected to be least affected by the terrestrial heat radiation from the orbit conditions, and also analyze difference of the output current for a month from that for the same month in the previous year. The analysis method leads us to successfully track a continuous correlation between the decease rate of solar cell output and energetic trapped proton flux up to 1996. We also discuss the best-fitted spatial distribution of energetic protons from comparison with model calculations.

  8. H. Julian Allen

    NASA Technical Reports Server (NTRS)

    1957-01-01

    H. Julian Allen stands beside the observation window of the 8 x 7 foot test section of the NACA Ames Unitary Plan Wind Tunnel. H. Julian Allen is best known for his 'Blunt Body Theory' of aerodynamics, a design technique for alleviating the severe re-entry heating problem which was then delaying the development of ballistic missiles. His findings revolutionized the fundamental design of ballistic missle re-entry shapes. Subsequently, applied research led to applications of the 'blunt' shape to ballistic missles and spacecraft which were intended to re-enter the Earth's atmosphere. This application led to the design of ablative heat shields that protected the Mercury, Gemini and Apollo astronauts as their space capsules re- entered the Earth's atmosphere. 'Harvey' Allen as he was called by most, was not only a brilliant scientist and aeronautical engineer but was also admired for his kindness, thoughtfulness and sense of humor. Among his many other accomplishments, Harvey Allen served as Center Director of the NASA Ames Research Center from 1965 to 1969. He died of a heart attack on January 29, 1977 at the age of 66.

  9. A Maximum Likelihood Ensemble Data Assimilation Method Tailored to the Inner Radiation Belt

    NASA Astrophysics Data System (ADS)

    Guild, T. B.; O'Brien, T. P., III; Mazur, J. E.

    2014-12-01

    The Earth's radiation belts are composed of energetic protons and electrons whose fluxes span many orders of magnitude, whose distributions are log-normal, and where data-model differences can be large and also log-normal. This physical system thus challenges standard data assimilation methods relying on underlying assumptions of Gaussian distributions of measurements and data-model differences, where innovations to the model are small. We have therefore developed a data assimilation method tailored to these properties of the inner radiation belt, analogous to the ensemble Kalman filter but for the unique cases of non-Gaussian model and measurement errors, and non-linear model and measurement distributions. We apply this method to the inner radiation belt proton populations, using the SIZM inner belt model [Selesnick et al., 2007] and SAMPEX/PET and HEO proton observations to select the most likely ensemble members contributing to the state of the inner belt. We will describe the algorithm, the method of generating ensemble members, our choice of minimizing the difference between instrument counts not phase space densities, and demonstrate the method with our reanalysis of the inner radiation belt throughout solar cycle 23. We will report on progress to continue our assimilation into solar cycle 24 using the Van Allen Probes/RPS observations.

  10. Results from the magnetic electron ion spectrometer (MagEIS) instruments aboard the Van Allen Probes spacecraft

    NASA Astrophysics Data System (ADS)

    Fennell, Joseph; O'Brien, Paul; Roeder, James; Reeves, Geoffrey; Claudepierre, Seth; Clemmons, James; Spence, Harlan; Blake, Bernard

    The Magnetic Electron Ion Spectrometer (MagEIS) instruments aboard the Van Allen Probes Spacecraft (formerly RBSP) measure electrons and ions in the Earth's inner and outer radiation belts. The MagEIS instruments are part of the Energetic Particle, Composition, and Thermal Plasma Suite (ECT), which also includes the Relativistic Electron Proton Telescope (REPT) and the Helium Oxygen Proton Electron (HOPE) analyzer. MagEIS consists of four magnetic electron spectrometers aboard each of the two Van Allen Probes spacecraft that measure the differential fluxes, energies, and angular distributions of electrons from 20 keV to 4 MeV. The MagEIS suite also contains a silicon-detector telescope that measures the differential fluxes, energies, and angular distributions of protons from 60 keV to 20 MeV, and helium and oxygen ions above a hundred keV/AMU. We briefly describe the instrument design and measurement technique and present a set of results from the MagEIS observations, including ultra-low frequency (ULF) modulations of energetic electron flux, and observations of electron flux enhancements associated with the recent BARREL x-ray observations.

  11. Survival of bacterial isolates exposed to simulated Jovian trapped radiation belt electrons and solar wind protons

    NASA Technical Reports Server (NTRS)

    Taylor, D. M.; Hagen, C. A.; Renninger, G. M.; Simko, G. J.; Smith, C. D.; Yelinek, J. A.

    1972-01-01

    With missions to Jupiter, the spacecraft will be exposed for extended duration to solar wind radiation and the Jovian trapped radiation belt. This study is designed to determine the effect of these radiation environments on spacecraft bacterial isolates. The information can be used in the probability of contamination analysis for these missions. A bacterial subpopulation from Mariner Mars 1971 spacecraft (nine sporeforming and three nonsporeforming isolates) plus two comparative organisms, Staphylococcus epidermidis ATCC 17917 and a strain of Bacillus subtilis var. niger, were exposed to 2-, 12-, and 25-MeV electrons at different doses with simultaneous exposure to a vacuum of 0.0013 N/sqm at 20 and -20 C. The radioresistance of the subpopulation was dependent on the isolate, dose, and energy of electrons. Temperature affected the radioresistance of only the sporeforming isolates. Survival data indicated that spores were reduced approximately 1 log/1500 J/kg, while nonsporeforming isolates (micrococci) were reduced 1.5 to 2 logs/1500 J/kg with the exception of an apparent radioresistant isolate whose resistance approached that of the spores. The subpopulation was found to be less resistant to lower energy than to higher energy electrons.

  12. Electron Flux of Radiation Belts Animation

    NASA Video Gallery

    This animation shows meridional (from north-south) plane projections of the REPT-A and REPT-B electron flux values. The animation first shows the expected two-belt Van Allen zone structure; from Se...

  13. Simultaneous quiet time observations of energetic radiation belt protons and helium ions - The equatorial alpha/p ratio near 1 MeV

    NASA Technical Reports Server (NTRS)

    Fritz, T. A.; Spjeldvik, W. N.

    1979-01-01

    Simultaneous monitoring of energetic helium ions and protons in the earth's radiation belts has been conducted with Explorer 45 in the immediate vicinity of the equatorial plane. Protons were measured from less than 1 keV to 1.6 MeV and also above 3.3 MeV in a channel responsive up to 22 MeV; helium ions were monitored in three passbands: 910 keV to 3.15 MeV, 590 to 910 keV, and 2.0 to 3.99 MeV. Alpha/proton flux ratios were found to vary significantly with energy and location in the radiation belts. At equal energy per nucleon a range of variability for alpha/p from 0.0001 to well above 0.001 was found, and at equal energy per ion the corresponding variability was from 0.001 to above 10. The latter findings emphasize the relative importance of the very energetic helium ions in the overall radiation belt ion populations.

  14. Van Allen Probes ECT/MagEIS Background Corrected Electron Flux Measurements: Methods and Initial Findings

    NASA Astrophysics Data System (ADS)

    Claudepierre, S. G.; O'Brien, T. P., III; Blake, J. B.; Fennell, J.; Looper, M. D.; Clemmons, J. H.; Roeder, J. L.; Mazur, J. E.; Mulligan, T. L.

    2014-12-01

    We present results from the Magnetic Electron Ion Spectrometer (MagEIS) instrument, part ofthe Energetic Composition and Thermal Plasma (ECT) Suite, onboard the NASA Van AllenProbes spacecraft. The ECT/MagEIS instrument measures radiation belt electrons in the ~20-4000 keV energy range and protons in the ~60-1000 keV energy range, with high resolution inboth energy and pitch-angle. In addition, the MagEIS electron measurement technique allowsfor a full quantification of the source(s) of background contamination in the measurement.MagEIS is thus able to make clean, reliable electron flux observations in the presence of strongpenetrating backgrounds, for example, contamination from relativistic protons in the inner zoneand inner slot region. We summarize our background correction algorithm, describe the varioussources of background contamination, and present an overview of our initial findings using thebackground corrected data set. Understanding the causes and effects of backgroundcontamination in the MagEIS electron data set is crucial for the interpretation and proper use ofsuch data. The techniques described will facilitate new investigations into the dynamics of theEarth's electron radiation belts, which have thus far not been possible.

  15. The Evolving Space Weather System—Van Allen Probes Contribution

    NASA Astrophysics Data System (ADS)

    Zanetti, L. J.; Mauk, B. H.; Fox, N. J.; Barnes, R. J.; Weiss, M.; Sotirelis, T. S.; Raouafi, N.-E.; Kessel, R. L.; Becker, H. N.

    2014-10-01

    The overarching goal and purpose of the study of space weather is clear—to understand and address the issues caused by solar disturbances on humans and technological systems. Space weather has evolved in the past few decades from a collection of concerned agencies and researchers to a critical function of the National Weather Service of NOAA. The general effects have also evolved from the well-known telegraph disruptions of the mid-1800s to modern day disturbances of the electric power grid, communications and navigation, human spaceflight and spacecraft systems. The last two items in this list, and specifically the effects of penetrating radiation, were the impetus for the space weather broadcast implemented on NASA's Van Allen Probes' twin pair of satellites, launched in August of 2012 and orbiting directly through Earth's severe radiation belts. The Van Allen Probes mission, formerly the Radiation Belt Storm Probes (RBSP), was renamed soon after launch to honor the discoverer of Earth's radiation belts at the beginning of the space age, the late James Van Allen (the spacecraft themselves are still referred to as RBSP-A and RBSP-B). The Van Allen Probes are one part of NASA's Living With a Star program formulated to advance the scientific understanding of the connection between solar disturbances, the resulting heliospheric conditions, and their effects on the geospace and Earth environment.

  16. EPICS: Allen-Bradley hardware reference manual

    SciTech Connect

    Nawrocki, G.

    1993-04-05

    This manual covers the following hardware: Allen-Bradley 6008 -- SV VMEbus I/O scanner; Allen-Bradley universal I/O chassis 1771-A1B, -A2B, -A3B, and -A4B; Allen-Bradley power supply module 1771-P4S; Allen-Bradley 1771-ASB remote I/O adapter module; Allen-Bradley 1771-IFE analog input module; Allen-Bradley 1771-OFE analog output module; Allen-Bradley 1771-IG(D) TTL input module; Allen-Bradley 1771-OG(d) TTL output; Allen-Bradley 1771-IQ DC selectable input module; Allen-Bradley 1771-OW contact output module; Allen-Bradley 1771-IBD DC (10--30V) input module; Allen-Bradley 1771-OBD DC (10--60V) output module; Allen-Bradley 1771-IXE thermocouple/millivolt input module; and the Allen-Bradley 2705 RediPANEL push button module.

  17. Time variations of proton flux in Earth inner radiation belt during 23/24 solar cycles based on the PAMELA and the ARINA data

    NASA Astrophysics Data System (ADS)

    Malakhov, V. V.; Koldashov, S. V.; Mayorov, A. G.; Mayorova, M. A.; Mikhailov, V. V.; Aleksandrin, S. Yu; Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Boezio, M.; Bogomolov, E. A.; Bongi, M.; Bonvicini, V.; Bottai, S.; Bruno, A.; Cafagna, F.; Campana, D.; Carlson, P.; Casolino, M.; Castellini, G.; De Donato, C.; De Santis, C.; De Simone, N.; Di Felice, V.; Formato, V.; Galper, A. M.; Karelin, A. V.; Krutkov, S. Yu; Kvashnin, A. A.; Kvashnin, A. N.; Leonov, A. A.; Marcelli, L.; Martucci, M.; Menn, W.; Merge, M.; Mocchuuitti, E.; Monaco, A.; Mori, N.; Munini, R.; Osteria, G.; Palma, F.; Panico, B.; Papini, P.; Pearce, M.; Picozza, P.; Ricci, M.; Ricciarini, S. B.; Sarkar, R.; Scotti, V.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stozhkov, Yu I.; Vacci, A.; Vannuccini, E.; Vasilyev, G. I.; Voronov, S. A.; Yurkin, Yu T.; Zampa, G.; Zampa, N.

    2015-08-01

    The PAMELA and the ARINA experiments are carried out on the board of satellite RESURS-DK1 since 2006 up to now. Main goal of the PAMELA instrument is measurements of high energy antiparticles in cosmic rays while the ARINA instrument is intended studying high energy charged particle bursts in the magnetosphere. Both of these experiments have a possibility to study trapped particles in the inner radiation belt. Complex of these two instruments covers proton energy range from 30 MeV up to trapping limit (E= ∼2 GeV). Continuous measurements with the PAMELA and the ARINA spectrometers include falling and rising phases of 23/24 solar cycles and maximum of 24th one. In this report we present temporal profiles of proton flux in the inner zone of the radiation belt (1.11 < L < 1.18, 0.18 < B < 0.22G). Dependence of proton fluxes on a magnitude of the solar activity was studied for various phases of 23/24 solar cycles. At that it was shown that proton fluxes at the solar minimum are several times greater than at the solar maximum.

  18. Recent Science Highlights of the Van Allen Probes Mission

    NASA Astrophysics Data System (ADS)

    Ukhorskiy, Aleksandr

    2016-10-01

    The morning of 30 August 2012 saw an Atlas 5 rocket launch NASA's second Living With a Star spacecraft mission, the twin Radiation Belt Storm Probes, into an elliptic orbit cutting through Earth's radiation belts. Renamed the Van Allen Probes soon after launch, the Probes are designed to determine how the highly variable populations of high-energy charged particles within the radiation belts, dangerous to astronauts and satellites, are created, respond to solar variations, and evolve in space environments. The Van Allen Probes mission extends beyond the practical considerations of the hazard's of Earth's space environment. Twentieth century observations of space and astrophysical systems throughout the solar system and out into the observable universe have shown that the processes that generate intense particle radiation within magnetized environments such as Earth's are universal. During its mission the Van Allen Probes verified and quantified previously suggested energization processes, discovered new energization mechanisms, revealed the critical importance of dynamic plasma injections into the innermost magnetosphere, and used uniquely capable instruments to reveal inner radiation belt features that were all but invisible to previous sensors. This paper gives a brief overview of the mission, presents some recent science highlights, and discusses plans for the extended mission.

  19. The Global Positioning System constellation as a space weather monitor. Comparison of electron measurements with Van Allen Probes data

    DOE PAGES

    Morley, Steven K.; Sullivan, John P.; Henderson, Michael G.; ...

    2016-02-06

    Energetic electron observations in Earth's radiation belts are typically sparse, and multipoint studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of the Combined X-ray Dosimeter (CXD), currently flown on 19 satellites in the Global Positioning System (GPS) constellation, by cross-calibrating energetic electron measurements against data from the Van Allen Probes. By breaking our cross calibration into two parts—one that removes any spectral assumptions from the CXD flux calculation and one that compares the energy spectra—we first validate the modeled instrument response functions, then the calculated electron fluxes. Unlike previous forward modeling of energetic electron spectra, wemore » use a combination of four distributions that together capture a wide range of observed spectral shapes. Moreover, our two-step approach allowed us to identify, and correct for, small systematic offsets between block IIR and IIF satellites. Using the Magnetic Electron Ion Spectrometer and Relativistic Electron-Proton Telescope on Van Allen Probes as a “gold standard,” here we demonstrate that the CXD instruments are well understood. A robust statistical analysis shows that CXD and Van Allen Probes fluxes are similar and the measured fluxes from CXD are typically within a factor of 2 of Van Allen Probes at energies inline image4 MeV. Our team present data from 17 CXD-equipped GPS satellites covering the 2015 “St. Patrick's Day” geomagnetic storm to illustrate the scientific applications of such a high data density satellite constellation and therefore demonstrate that the GPS constellation is positioned to enable new insights in inner magnetospheric physics and space weather forecasting.« less

  20. The Global Positioning System constellation as a space weather monitor. Comparison of electron measurements with Van Allen Probes data

    SciTech Connect

    Morley, Steven K.; Sullivan, John P.; Henderson, Michael G.; Blake, J. Bernard; Baker, Daniel N.

    2016-02-06

    Energetic electron observations in Earth's radiation belts are typically sparse, and multipoint studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of the Combined X-ray Dosimeter (CXD), currently flown on 19 satellites in the Global Positioning System (GPS) constellation, by cross-calibrating energetic electron measurements against data from the Van Allen Probes. By breaking our cross calibration into two parts—one that removes any spectral assumptions from the CXD flux calculation and one that compares the energy spectra—we first validate the modeled instrument response functions, then the calculated electron fluxes. Unlike previous forward modeling of energetic electron spectra, we use a combination of four distributions that together capture a wide range of observed spectral shapes. Moreover, our two-step approach allowed us to identify, and correct for, small systematic offsets between block IIR and IIF satellites. Using the Magnetic Electron Ion Spectrometer and Relativistic Electron-Proton Telescope on Van Allen Probes as a “gold standard,” here we demonstrate that the CXD instruments are well understood. A robust statistical analysis shows that CXD and Van Allen Probes fluxes are similar and the measured fluxes from CXD are typically within a factor of 2 of Van Allen Probes at energies inline image4 MeV. Our team present data from 17 CXD-equipped GPS satellites covering the 2015 “St. Patrick's Day” geomagnetic storm to illustrate the scientific applications of such a high data density satellite constellation and therefore demonstrate that the GPS constellation is positioned to enable new insights in inner magnetospheric physics and space weather forecasting.

  1. The evolution of ring current ion energy density and energy content during geomagnetic storms based on Van Allen Probes measurements

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Baker, D. N.; Fennell, J. F.; Blake, J. B.; Larsen, B. A.; Skoug, R. M.; Funsten, H. O.; Friedel, R. H. W.; Reeves, G. D.; Spence, H. E.; Mitchell, D. G.; Lanzerotti, L. J.; Rodriguez, J. V.

    2015-09-01

    Enabled by the comprehensive measurements from the Magnetic Electron Ion Spectrometer (MagEIS), Helium Oxygen Proton Electron mass spectrometer (HOPE), and Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of ions with different energies and species to the ring current energy density and their dependence on the phases of geomagnetic storms are quantified. The results show that lower energy (<50 keV) protons enhance much more often and also decay much faster than higher-energy protons. During the storm main phase, ions with energies <50 keV contribute more significantly to the ring current than those with higher energies; while the higher-energy protons dominate during the recovery phase and quiet times. The enhancements of higher-energy proton fluxes as well as energy content generally occur later than those of lower energy protons, which could be due to the inward radial diffusion. For the 29 March 2013 storm we investigated in detail that the contribution from O+ is ~25% of the ring current energy content during the main phase and the majority of that comes from <50 keV O+. This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions. Using the Dessler-Parker-Sckopke relation, the contributions of ring current particles to the magnetic field depression during this geomagnetic storm are also calculated. The results show that the measured ring current ions contribute about half of the Dst depression.

  2. Comparison of species-resolved energy spectra from ACE EPAM and Van Allen Probes RBSPICE

    NASA Astrophysics Data System (ADS)

    Patterson, J.; Manweiler, J. W.; Armstrong, T. P.; Lanzerotti, L. J.; Gerrard, A. J.; Gkioulidou, M.

    2013-12-01

    We present a comparison between energy spectra measured by the Advanced Composition Explorer (ACE) Electron Proton Alpha Monitor (EPAM) instrument and the Van Allen Probe Ion Composition Experiment (RBSPICE) for two significant and distinct events in early 2013. The first is an impulsive solar particle event on March 17th. While intense, this event presented no significant surprises in terms of its composition or anisotropy characteristics, thus providing a good baseline for response of the trapped radiation belts as observed by the Van Allen Probes. The second solar event occurred late May 22nd and early May 23rd. This event has a much greater concentration of medium and heavy ions than the St. Patrick's Day event, as well as having very peculiar energy spectra with evidence of two distinct populations. During the St. Patrick's Day Event, the energy spectra for helium, carbon, oxygen, neon, silicon, and iron all show the same spectral power law slope -3.1. The event shows strong anisotropy with intensities differing by a factor of four for both protons and Z>1 ions. The late May event also has strong anisotropy, and in the same directions as the St. Patrick's Day Event, but with very different composition and energy spectra. The spectra are much harder with power law spectral slopes of -0.5. Additionally, there is a significant spectral bump at 3 MeV/nuc for helium that is not present in the spectra of the heavier ions. The intensities of the heavier ions, however, show an increase that is an order of magnitude greater than the increase seen for helium. The March 17 RBSPICE observations show multiple injection events lasting for less than an hour each during the Van Allen Probes B apogees. These injections are seen in protons as well as Helium and only somewhat observed in Oxygen. Spectral slopes for the observations range from approximately -5 during quiet times to double peaked events with a spectral slope of approximately -2 at the beginning of the injection

  3. UK-5 Van Allen belt radiation exposure: A special study to determine the trapped particle intensities on the UK-5 satellite with spatial mapping of the ambient flux environment

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.

    1972-01-01

    Vehicle encountered electron and proton fluxes were calculated for a set of nominal UK-5 trajectories with new computational methods and new electron environment models. Temporal variations in the electron data were considered and partially accounted for. Field strength calculations were performed with an extrapolated model on the basis of linear secular variation predictions. Tabular maps for selected electron and proton energies were constructed as functions of latitude and longitude for specified altitudes. Orbital flux integration results are presented in graphical and tabular form; they are analyzed, explained, and discussed.

  4. Analysis of a non-storm time enhancement in outer belt electrons

    NASA Astrophysics Data System (ADS)

    Schiller, Q.; Li, X.; Godinez, H. C.; Sarris, T. E.; Tu, W.; Malaspina, D.; Turner, D. L.; Blake, J. B.; Koller, J.

    2014-12-01

    A high-speed solar wind stream impacted Earth's magnetosphere on January 13th, 2013, and is associated with a large enhancement (>2.5 orders) of outer radiation belt electron fluxes despite a small Dst signature (-30 nT). Fortunately, the outer belt was well sampled by a variety of missions during the event, including the Van Allen Probes, THEMIS, and the Colorado Student Space Weather Experiment (CSSWE). In-situ flux and phase space density observations are used from MagEIS (Magnetic Electron Ion Spectrometer) onboard the Van Allen Probes, REPTile (Relativistic Electron and Proton Telescope integrated little experiment) onboard CSSWE, and SST onboard THEMIS. The observations show a rapid increase in 100's keV electron fluxes, followed by a more gradual enhancement of the MeV energies. The 100's keV enhancement is associated with a substorm injection, and the futher energization to MeV energies is associated with wave activity as measured by the Van Allen Probes and THEMIS. Furthermore, the phase space density radial profiles show an acceleration region occurring between 5

  5. A non-storm time enhancement of outer radiation belt electrons

    NASA Astrophysics Data System (ADS)

    Schiller, Q.; Li, X.; Blum, L. W.; Jaynes, A. N.; Malaspina, D.; Tu, W.; Turner, D. L.; Blake, J. B.

    2013-12-01

    On January 13th, 2013, a high-speed solar wind stream impacted Earth's magnetosphere, resulting in low geomagnetic activity (Real-Time Dst minimum of -30 nT). However, the relativistic electron population was enhanced by over two orders of magnitude in the outer radiation belt. Fortunately, during the event, the outer belt was well sampled by a variety of missions, including the Van Allen Probes, THEMIS, GOES, and the Colorado Student Space Weather Experiment (CSSWE). The energetic electrons are measured in-situ using flux and phase space density observations from the Magnetic Electron Ion Spectrometer (MagEIS) onboard the Van Allen Probes, the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) onboard CSSWE, and SST onboard THEMIS. These measured electron populations are the net result of the balance between concurrent loss and acceleration processes. Precipitation loss is quantified using REPTile measurements at low altitudes, while the energization mechanisms, namely interactions with whistler-mode chorus and Pc5 ULF waves, are investigated using Van Allen Probes' MagEIS and Electric Fields and Waves Suite (EFW), THEMIS' EFI and SCM instrument suites, and GOES magnetometers. The quantity and quality of measurements during this event provide a rare opportunity to address outstanding science questions; such as, whether the energetic electrons originate from inward injections associated with substorms or are accelerated via local heating, as well as what the energy dependence of the enhancement is during a period of such low geomagnetic activity.

  6. A background correction algorithm for Van Allen Probes MagEIS electron flux measurements

    SciTech Connect

    Claudepierre, S. G.; O'Brien, T. P.; Blake, J. B.; Fennell, J. F.; Roeder, J. L.; Clemmons, J. H.; Looper, M. D.; Mazur, J. E.; Mulligan, T. M.; Spence, H. E.; Reeves, G. D.; Friedel, R. H. W.; Henderson, M. G.; Larsen, B. A.

    2015-07-14

    We describe an automated computer algorithm designed to remove background contamination from the Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS) electron flux measurements. We provide a detailed description of the algorithm with illustrative examples from on-orbit data. We find two primary sources of background contamination in the MagEIS electron data: inner zone protons and bremsstrahlung X-rays generated by energetic electrons interacting with the spacecraft material. Bremsstrahlung X-rays primarily produce contamination in the lower energy MagEIS electron channels (~30–500 keV) and in regions of geospace where multi-M eV electrons are present. Inner zone protons produce contamination in all MagEIS energy channels at roughly L < 2.5. The background-corrected MagEIS electron data produce a more accurate measurement of the electron radiation belts, as most earlier measurements suffer from unquantifiable and uncorrectable contamination in this harsh region of the near-Earth space environment. These background-corrected data will also be useful for spacecraft engineering purposes, providing ground truth for the near-Earth electron environment and informing the next generation of spacecraft design models (e.g., AE9).

  7. A background correction algorithm for Van Allen Probes MagEIS electron flux measurements

    DOE PAGES

    Claudepierre, S. G.; O'Brien, T. P.; Blake, J. B.; ...

    2015-07-14

    We describe an automated computer algorithm designed to remove background contamination from the Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS) electron flux measurements. We provide a detailed description of the algorithm with illustrative examples from on-orbit data. We find two primary sources of background contamination in the MagEIS electron data: inner zone protons and bremsstrahlung X-rays generated by energetic electrons interacting with the spacecraft material. Bremsstrahlung X-rays primarily produce contamination in the lower energy MagEIS electron channels (~30–500 keV) and in regions of geospace where multi-M eV electrons are present. Inner zone protons produce contamination in all MagEIS energymore » channels at roughly L < 2.5. The background-corrected MagEIS electron data produce a more accurate measurement of the electron radiation belts, as most earlier measurements suffer from unquantifiable and uncorrectable contamination in this harsh region of the near-Earth space environment. These background-corrected data will also be useful for spacecraft engineering purposes, providing ground truth for the near-Earth electron environment and informing the next generation of spacecraft design models (e.g., AE9).« less

  8. Prompt injections of highly relativistic electrons induced by interplanetary shocks: A statistical study of Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Schiller, Q.; Kanekal, S. G.; Jian, L. K.; Li, X.; Jones, A.; Baker, D. N.; Jaynes, A.; Spence, H. E.

    2016-12-01

    We conduct a statistical study on the sudden response of outer radiation belt electrons due to interplanetary (IP) shocks during the Van Allen Probes era, i.e., 2012 to 2015. Data from the Relativistic Electron-Proton Telescope instrument on board Van Allen Probes are used to investigate the highly relativistic electron response (E > 1.8 MeV) within the first few minutes after shock impact. We investigate the relationship of IP shock parameters, such as Mach number, with the highly relativistic electron response, including spectral properties and radial location of the shock-induced injection. We find that the driving solar wind structure of the shock does not affect occurrence for enhancement events, 25% of IP shocks are associated with prompt energization, and 14% are associated with MeV electron depletion. Parameters that represent IP shock strength are found to correlate best with highest levels of energization, suggesting that shock strength may play a key role in the severity of the enhancements. However, not every shock results in an enhancement, indicating that magnetospheric preconditioning may be required.

  9. Orion GNC Mitigation Efforts for Van Allen Radiation

    NASA Technical Reports Server (NTRS)

    King, Ellis T.; Jackson, Mark

    2013-01-01

    The Orion Crew Module (CM) is NASA's next generation manned space vehicle, scheduled to return humans to lunar orbit in the coming decade. The Orion avionics and GN&C architectures have progressed through a number of project phases and are nearing completion of a major milestone. The first unmanned test mission, dubbed "Exploration Flight Test One" (EFT-1) is scheduled to launch from NASA Kennedy Space Center late next year and provides the first integrated test of all the vehicle systems, avionics and software. The EFT-1 mission will be an unmanned test flight that includes a high speed re-entry from an elliptical orbit, which will be launched on an expendable launch vehicle (ELV). The ELV will place CM and the ELV upper stage into a low Earth orbit (LEO) for one revolution. After the first LEO, the ELV upper stage will re-ignite and place the combined upper stage/CM into an elliptical orbit whose perigee results in a high energy entry to test CM response in a relatively high velocity, high heating environment. While not producing entry velocities as high as those experienced in returning from a lunar orbit, the trajectory was chosen to provide higher stresses on the thermal protection and guided entry systems, as compared against a lower energy LEO entry. However the required entry geometry with constraints on inclination and landing site result in a trajectory that lingers for many hours in the Van Allen radiation belts. This exposes the vehicle and avionics to much higher levels of high energy proton radiation than a typical LEO or lunar trajectory would encounter. As a result, Van Allen radiation poses a significant risk to the Orion avionics system, and particularly the Flight Control Module (FCM) computers that house the GN&C flight software. The measures taken by the Orion GN&C, Flight Software and Avionics teams to mitigate the risks associated with the Van Allen radiation on EFT-1 are covered in the paper. Background on the Orion avionics subsystem is

  10. Inner Radiation Belt Data Assimilation

    NASA Astrophysics Data System (ADS)

    Guild, Timothy; Selesnick, Richard; Mazur, Joseph

    We present preliminary results of inner belt proton data assimilation using an augmented ver-sion of the Selesnick et al., [2007] model. The physics-based model computes inner belt proton intensities as a function of time and of the three adiabatic invariants M, K, and L according to a comprehensive list of inner belt source and loss processes. We modify the model solution based on in-situ proton observations and according to a data-assimilation method which exploits the non-Gaussian nature of inner belt proton intensities and Poisson or Gaussian counting statistics of the observations, as appropriate. We demonstrate the method by presenting data-assimilated inner belt proton intensities during a solar particle injection.

  11. Inner Radiation Belt Data Assimilation

    NASA Astrophysics Data System (ADS)

    Guild, T. B.; O'Brien, T. P.

    2011-12-01

    We present preliminary results of inner belt proton data assimilation using an augmented version of the Selesnick Inner Zone Model (SIZM). The physics-based model computes inner belt proton intensities as a function of time and of the three adiabatic invariants M, K, and L according to a comprehensive list of inner belt source and loss processes. We modify the model solution based on in-situ proton observations from SAMPEX/PET and HEO orbit and according to a data-assimilation method which exploits the non-Gaussian nature of inner belt proton intensities and Poisson or Gaussian counting statistics of the observations, as appropriate. We demonstrate the method by presenting data-assimilated inner belt proton intensities during a solar particle injection.

  12. Inner Radiation Belt Data Assimilation

    NASA Astrophysics Data System (ADS)

    Guild, T. B.; O'Brien, T. P.; Mazur, J. E.

    2010-12-01

    We present preliminary results of inner belt proton data assimilation using an augmented version of the Selesnick et al., [2007] model. The physics-based model computes inner belt proton intensities as a function of time and of the three adiabatic invariants M, K, and L according to a comprehensive list of inner belt source and loss processes. We modify the model solution based on in-situ proton observations and according to a data-assimilation method which exploits the non-Gaussian nature of inner belt proton intensities and Poisson or Gaussian counting statistics of the observations, as appropriate. We demonstrate the method by presenting data-assimilated inner belt proton intensities during a solar particle injection.

  13. Drifting Quasi-Periodic Modulation of the Fast Magnetosonic Mode: Van Allen Probe Observations

    NASA Astrophysics Data System (ADS)

    Boardsen, S. A.; Hospodarsky, G. B.; Kletzing, C.; Pfaff, R. F., Jr.; Kurth, W. S.; Wygant, J. R.; MacDonald, E.

    2014-12-01

    The fast magnetosonic mode is one of the dominant wave modes in the Earth's radiation belts. These waves influence the ring current by scattering ions in energy in the 10's of keV range, and are believed to be a heat source for radiation belt electrons. The fast magnetosonic mode observed around the Earth's inner equatorial magnetosphere sometimes exhibits quasi-periodic modulation as detected by the Van Allen probes. During each modulation the wave frequency exhibits a strong drifting (dispersive) signature characterized by a rising tone. Each tone is composed of harmonics with spacing close to the proton cyclotron frequency. The tones are band limited in frequency and mainly observed above the 20th harmonic of the local proton cyclotron frequency. We observe this modulation mainly outside the plasmapause, but it has also been observed to penetrate down to 1.5 RE. The modulation is observed up to magnetic latitudes of ±17º, at all magnetic local times, but its signatures are more pronounced on the dayside. For events where lower frequency ULF waves are detected, the period of the ULF wave is about twice the modulation period of the fast magnetosonic mode, suggesting strong wave-wave interactions. The modulation period varies from 50 to 200 s and its duration ranges from 0.2 to 3 h, with the maximum duration limited by the spacecraft orbit. We hypothesize that the rising tone is produced by changing Alfven velocities created by steepened density fluctuations due to plasma modification by an underlying ULF wave.

  14. Obituary: James Alfred Van Allen, 1914-2006

    NASA Astrophysics Data System (ADS)

    Ludwig, George H.; McIlwain, Carl Edwin

    2006-12-01

    successful field expeditions from 1952 through 1957. As the prospect for launching Earth satellites began to materialize, Van Allen became an enthusiastic participant in planning and executing the U.S. program. After gaining a spot on the short list of initial experiments for the Vanguard satellite program, development of the cosmic ray instrument that he had proposed became a high laboratory priority. That instrument was launched in abbreviated form by an Army Jupiter C vehicle as Explorer I on 31 January 1958, and the full version was launched less than two months later as Explorer III. The two satellites resulted in what Van Allen considered the crowning event of his long and distinguished career — the discovery, with his university associates, of the bands of intense radiation that surround the Earth, now known as the "Van Allen Radiation Belts." Van Allen continued to take a leading role in extending space research beyond Earth's orbit. His group sent instruments to the Moon, Venus, Mars, Jupiter, Saturn, and throughout interplanetary space. During his outstandingly productive career, Van Allen served as principal investigator on more than twenty-five space science missions. James Van Allen was the consummate teacher and mentor. Years ago, when asked how he would most like to be remembered, he replied simply, "As a teacher." He supervised the preparation of forty-eight master's and thirty-four doctor's theses by sixty different individuals. He gave those graduate students extraordinary freedom and responsibility in the conduct of their projects. He always treated his students, both undergraduate and graduate, with respect, listening to them, learning from them, and guiding them with wisdom and kindness. The folksy, pipe-smoking scientist worked from 1951 until 1964 in a modest office on the second floor of the old Physics and Mathematics building. He maintained his own private laboratory, where he continued to spend many hours with hands-on work at the bench. When the

  15. CubeSat-Associated Radiation Belt Research: Recent and Upcoming Observations

    NASA Astrophysics Data System (ADS)

    Blum, Lauren; Li, Xinlin; Schiller, Quintin

    2016-07-01

    Interest in CubeSats has grown dramatically in the past decade within the space physics community. While CubeSats are generally accepted now to be useful tools for education and technology development/demonstration, their ability to provide scientific value is often still questioned. Radiation belt physics, however, is one area in which the scientific utility of these small platforms has been demonstrated and continues to offer great promise. The Colorado Student Space Weather Experiment (CSSWE) CubeSat, designed, built, tested, and operated by students at University of Colorado with mentoring from LASP professionals, was one of the first of now a long line of CubeSats designed to study radiation belt dynamics. Launched in September 2012, just a few weeks after NASA's Van Allen Probes, CSSWE provided valuable measurements of energetic electrons and protons from low-Earth orbit for two years, well beyond its nominal 3-month mission lifetime. The status of and results from CSSWE will be presented, with an emphasis on how these measurements have been combined with those from balloons and larger satellite missions to better understand radiation belt electron acceleration and loss processes. Some highlights from other radiation belt-related CubeSats will also be presented, along with upcoming missions. Radiation belt studies are a prime example of how small inexpensive CubeSats can be used to provide valuable scientific measurements and complement larger missions.

  16. ACE EPAM and Van Allen Probes RBSPICE measurements of interplanetary oxygen injection to the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Patterson, J. D.; Manweiler, J. W.; Gerrard, A. J.; Lanzerotti, L. J.

    2015-12-01

    On March 17, 2015, a significant oxygen-rich interplanetary event was measure by the Advanced Composition Explorer (ACE) Electron Proton Alpha Monitor (EPAM) instrument. At the same time the Van Allen Probes Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument recorded significant enhancements of oxygen in the inner magnetosphere. We present a detailed analysis of this event utilizing a new method of exploiting the EPAM Pulse Height Analyzer (PHA) data to precisely resolve helium and oxygen spectra within the 0.5 to 5 MeV/nuc range. We also present the flux, partial particle pressures, and pitch angle distributions of the ion measurements from RBSPICE. During this event, both EPAM and RBSPICE measured O:He ratios greater than 10:1. The pitch angle distributions from RBSPICE-B show a strong beam of oxygen at an L ~ 5.8 early on March 17th during orbit. The timing between the observations of the oxygen peak at ACE and the beam observed at RBSPICE-B is consistent with the travel-time required for energetic particle transport from L1 to Earth and access to the magnetosphere. We assert that the oxygen seen by RBSPICE during the initial phase of this event is the result of direct injection from the interplanetary medium of energetic ions. This poster contains the observations and detailed calculations to support this assertion.

  17. A Neural Network Approach for Identifying Relativistic Electron Pitch Angle Distributions in Van Allen Probes Data

    NASA Astrophysics Data System (ADS)

    Souza, V. M. C. E. S.; Vieira, L.; Alves, L. R.; Da Silva, L. A.; Koga, D.; Sibeck, D. G.; Walsh, B.; Kanekal, S. G.; Silveira, M. D.; Medeiros, C.; Mendes, O., Jr.; Marchezi, J.; Rockenbach, M.; Jauer, P. R.; Gonzalez, W.; Baker, D. N.

    2015-12-01

    A myriad of physical phenomena occur in the inner magnetosphere, in particular at the Earth's radiation belts, which can be a result of the combination of both internal and external processes. However, the connection between physical processes occurring deep within the magnetosphere and external interplanetary drivers it is not yet well understood. In this work we investigate whether a selected set of interplanetary structures affect the local time distribution of three different classes of high energy electron pitch angle distributions (PADs), namely normal, isotropic, and butterfly. We split this work into two parts: initially we focus on the methodology used which employs a Self-Organized Feature Map (SOFM) neural network for identifying different classes of electron PAD shapes in the Van Allen Probes' Relativistic Electron Proton Telescope (REPT) data. The algorithm can categorize the input data into an arbitrary number of classes from which three of them appears the most: normal, isotropic and butterfly. Other classes which are related with these three also emerge and deserve to be addressed in detail in future works. We also discuss the uncertainties of the algorithm. Then, we move to the second part where we describe in details the criteria used for selecting the interplanetary events, and also try to investigate the relation between key parameters characterizing such interplanetary structures and the local time distributions of electron PAD shapes.

  18. Reaction of oxygen with allene

    SciTech Connect

    Huang, Sheng-yu

    1988-07-01

    Elastic scattering studies carried out independently of the work related to the title forms the first section of the dissertation. The low-energy elastic scattering of He with Ar, Kr, Xe has been studied by molecular beam techniques. Two potential forms, exponential-spline-Morse-Morse-spline-van de Waals (ESMMSV) and Simon-Parr-Finlan-Dunham (SPFD), have been used to fit the measured differential cross section. Elastic scattering theory and experimental details are introduced. The reactive scattering of O(/sup 3/P) with allene has been studied using crossed molecular beams. Differing from the well known central-carbon-attack (CCA) mechanism in which the final products, carbon monoxide and ethylene, are obtained via a ring intermediate, a new mechanism, terminal-carbon-attack (TCA), has been observed. The production of O(/sup 3/P) atoms by radio frequency discharge is also introduced. To assist understanding of the experiments a multi-configuration self-consistent field (MCSCF) study of the reaction of O(/sup 3/P) with allene has been carried out. The key feature of the oxygen-allene potential energy surface for both CCA and TCA channels has been calculated with single-zeta (SZ), double-zeta (DZ), and double-zeta plus polarization (DZP) basis sets. Finally, an algorithm for optimizing the trial wavefunction in quantum Monte Carlo calculations has been developed. With the application of group theory, a symmetry-constrained optimization process can yield an improved trial wavefunction for the calculation of excited electronic state energies as well as the ground-state energy. Several applications are discussed. 145 refs.

  19. Radiation belts of jupiter.

    PubMed

    Stansberry, K G; White, R S

    1973-12-07

    Predictions of Jupiter's electron and proton radiation belts are based mainly on decimeter observations of 1966 and 1968. Extensive calculations modeling radial diffusion of particles inward from the solar wind and electron synchrotron radiation are used to relate the predictions and observations.

  20. Water resources of Allen Parish

    USGS Publications Warehouse

    Prakken, Lawrence B.; Griffith, Jason M.; Fendick, Robert B.

    2012-01-01

    In 2005, approximately 29.2 million gallons per day (Mgal/d) of water were withdrawn in Allen Parish, Louisiana, including about 26.8 Mgal/d from groundwater sources and 2.45 Mgal/d from surface-water sources. Rice irrigation accounted for 74 percent (21.7 Mgal/d) of the total water withdrawn. Other categories of use included public supply, industrial, rural domestic, livestock, general irrigation, and aquaculture. Water-use data collected at 5-year intervals from 1960 to 2005 indicate water withdrawals in the parish were greatest in 1960 (119 Mgal/d) and 1980 (98.7 Mgal/d). The substantial decrease in surface-water use between 1960 and 1965 is primarily attributable to rice-irrigation withdrawals declining from 61.2 to 6.74 Mgal/d. This fact sheet summarizes information on the water resources of Allen Parish, La. Information on groundwater and surface-water availability, quality, development, use, and trends is based on previously published reports listed in the Selected References section.

  1. Gradual Diffusion and Punctuated Phase Space Density Enhancements of Highly Relativistic Electrons: Van Allen Probes Observations

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Jaynes, A. N.; Li, X.; Henderson, M. G.; Kanekal, S. G.; Reeves, G. D.; Spence, H. E.; Claudepierre, S. G.; Fennell, J. F.; Hudson, M. K.

    2014-01-01

    The dual-spacecraft Van Allen Probes mission has provided a new window into mega electron volt (MeV) particle dynamics in the Earth's radiation belts. Observations (up to E (is) approximately 10MeV) show clearly the behavior of the outer electron radiation belt at different timescales: months-long periods of gradual inward radial diffusive transport and weak loss being punctuated by dramatic flux changes driven by strong solar wind transient events. We present analysis of multi-MeV electron flux and phase space density (PSD) changes during March 2013 in the context of the first year of Van Allen Probes operation. This March period demonstrates the classic signatures both of inward radial diffusive energization and abrupt localized acceleration deep within the outer Van Allen zone (L (is) approximately 4.0 +/- 0.5). This reveals graphically that both 'competing' mechanisms of multi-MeV electron energization are at play in the radiation belts, often acting almost concurrently or at least in rapid succession.

  2. "Inner electron" radiation belt: problems of model creation

    NASA Astrophysics Data System (ADS)

    Temnyi, V.

    The contents of intensive fluxes of trapped electrons J_e with energies E_e>40 keV in center of the inner terrestrial radiation belt is remains uncertain in model Vette AE-8, 1991. It is explained by methodical difficulties of discrete measurements of electrons by narrow-angle spectrometers with background from omnidirectional penetrating protons with energies E_p>40 MeV and electrons with E_e>1 MeV after STARFISH burst. The results of integral measurements of trapped electrons by 2 groups: Krassovsky V.I. on III Soviet satellite (May 1958) and J. Van Allen on EXPLORER-IV (July-August 1958) and on INJUN-1 (1961) heave given a performances concerning electron energy fluxes I_e(E_e>20 keV) ˜ (20-100) erg cm-2 c-1 into inner radiation belt. Improved integral measurements of electrons by Krassovsky group on satellites KOSMOS-3,-5 and ELECTRON-1,-3 (1962-1964) allow to determine the distributions of their intensities in the whole inner belt. They can add the central part of inner belt of AE-8 model (see report Bolunova et al., COSPAR-1965, publ. in SPACE RESEARCH VI, 1967, p. 649-661). From these data a maximum of trapped electrons J_e(E_e>40 keV)=2\\cdot10^9 cm-2 c-1 is placed on L=1,6, B/B_0=1. Intensities up to 2\\cdot10^7 cm-2 c-1 are determined only by coordinates (L, B). For smaller intensities become essential dependence from longitude along a drift shell. So, in the center of the inner radiation belt the energy fluxes I_e(E_e>40 keV) reach 500 erg cm-2 c-1 and density n_e=0,2 cm-3 while for trapped protons I_p(E_p>40 MeV) is less than 3 erg cm-2 c-1 and n_p< 5\\cdot10-6 cm-3. It forces to search a more powerful sources trapped electron than beta-decay of neutrons albedo of cosmic rays.

  3. The Evolution of Ring Current Energy Density and Energy Content during Geomagnetic Storms Based on Van Allen Probes Measurements

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Baker, D. N.; Claudepierre, S. G.; Fennell, J. F.; Blake, J. B.; Larsen, B.; Skoug, R. M.; Funsten, H. O.; Freidel, R. H. W.; Reeves, G. D.; Spence, H. E.; Mitchell, D. G.; Lanzerotti, L. J.; Rodriguez, J. V.

    2015-12-01

    Enabled by the comprehensive measurements from the MagEIS, HOPE, and RBSPICE instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of particles with different energies and species to the ring current energy density and their dependence on the geomagnetic storms and storm phases are quantified. During the main phases of moderate storms (with minimum Dst between -50 nT and -100 nT), ions of energies < 50 keV and electrons of energies of <35 keV contribute more significantly to the ring current energy than those of higher energies. During the recovery phase and quiet times higher energy protons dominate the ring current energy content. For the March 29, 2013 moderate storm, the contribution from O+ is ~25% of the ring current energy content during the main phase, and the majority of that comes from < 50 keV O+. This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions and low energy O+ plays an important role in ring current dynamics. The contribution of electrons to the ring current energy content is up to ~7% during this moderate storm and the magnetic local time dependence of electron energy density is also investigated. However, the ring current energy partitions for different species and energy ranges are very different during the great storm of 17 March 2015 (with minimum Dst<-210 nT).

  4. The Foundations of Radiation Belt Research

    NASA Astrophysics Data System (ADS)

    Ludwig, G. H.

    2008-12-01

    The United States undertook the launching of an artificial Earth satellite as part of its contribution to the International Geophysical Year. The Vanguard program was established to meet that commitment, and it developed a launch vehicle, ground station network, and suite of scientific payloads, including the cosmic ray experiment proposed by James A. Van Allen. Although Vanguard eventually exceeded all of its pre-stated goals, the preemptive launches of Sputniks I and II by the Soviets in October and November 1957 spurred the U.S. into a frenzy of activity, resulting in the launches of Explorers I and III in January and March of 1958. The data from those two satellites quickly revealed the lower boundary of an unexpected region of high intensity radiation trapped in the Earth's magnetic field. The original announcement in May 1958 stated that the radiation was probably composed of either protons or electrons, and that, if electrons, it was probably bremsstrahlung formed in the satellite shell. Immediately following that announcement, approval was received for what became Explorer IV, whose announced purpose was to follow up on the new discovery. Another reason for the satellite, unmentioned at the time, was its inclusion as a component of the highly classified Argos program, a covert military program to test whether the detonation of nuclear devices at high altitude would inject measurable numbers of charged particles into durable trajectories in the Earth's magnetic field. Our team at Iowa produced the satellites under the oversight of, and with assistance by, the Army Ballistic Missile Agency in Huntsville, and with the contributions of key hardware from several other government laboratories. The project was completed in the unbelievably short period of seventy-seven days from approval to launch. Launched into a higher-inclination orbit than the earlier Explorers, Explorer IV confirmed the discovery and greatly expanded our understanding of the natural

  5. Delayed effects of proton irradiation in Macaca Mulatta (22-year summary)

    NASA Astrophysics Data System (ADS)

    Woods, D. H.; Hardy, K. A.; Cox, A. B.; Salmon, Y. L.; Yochmowitz, M. G.; Cordts, R. E.

    1989-05-01

    Lifetime observations on a group of rhesus monkeys indicate that life expectancy loss from exposure to protons in the energy range encountered in the Van Allen belts and solar proton events can be correlated with the dose and energy of radiation. The primary cause of life shortening is nonleukemic cancers. Radiation also increased the rise of endometriosis (an abnormal proliferation of the lining of the uterus in females). Other effects associated with radiation exposures are lowered glucose tolerance and increased incidence of cataracts. Calculations of the relative risk of fatal cancers in the irradiated subjects reveal that the total body surface dose required to double the risk of death from cancer over a 20-year post exposure period varies with the linear energy transfer (LET) of the radiation. The ability to determine the integrated dose and LET spectrum in space radiation exposures of humans is, therefore, critical to the assessment of lifetime cancer risk.

  6. Statistical analysis of plasmaspheric magnetosonic mode waves from Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Nomura, K.; Miyoshi, Y.; Keika, K.; Shoji, M.; Kurita, S.; Kitamura, N.; Machida, S.; Santolik, O.; Kletzing, C.; Boardsen, S. A.

    2015-12-01

    Magnetosonic waves (MSWs) are electromagnetic emissions whose properites can be described by the cold plasma extraordinary mode, which are typically generated at frequencies (f) between the proton cyclotron frequency (fcp) and the lower hybrid resonant frequency. It has been suggested that MSWs can contribute to the acceleration of relativistic electrons in the radiation belts. In this study, we investigate the Poynting vector of plasmaspheric MSWs using the spectral matrix data from the EMFISIS instrument onboard the Van Allen Probes spacecraft. We derived the polarization and planarity from the spectrum matrix using the SVD method (Santolik et al., 2003) and also estimated the Poynting vector. The planarity is used as a proxy to distinguish presence of a single wave vector from mixture of waves propagating in different directions. The Poynting vector of MSWs with high planarity shows that the MSWs are observed to propagate radially as well as longitudinally. The occurrence probability of the propagation directions depends on the geomagnetic activities. During the geomagnetically quiet periods (Kp < 3), the percentage of inward, outward, and longitudinal propagations of MSWs at 60 Hz are 22%, 36% and 42% respectively. On the other hand, during the geomagnetically active periods (Kp > 5), the percentages are 53%, 21%, and 26%, respectively. The result indicates that the MSWs tend to propagate inward during the geomagnetically active periods. Since the fundamental frequency of the ion Bernstein mode would be local cyclotron frequency, we also investigate the source of MSWs from the minimum frequency of MSWs. It is found that a large number of MSWs tend to be generated at L=3.0-3.5 inside the plasmapause. We will also discuss the validity of the Poynting flux computation as a function of f/fcp.

  7. Belt-driven conveyor belts

    SciTech Connect

    Not Available

    1984-01-01

    An intermediate belt drive system offers a number of advantages over conventional systems, including lower power requirements and the ability to use lower quality, cheaper, conveyor belts. The advantages of a correctly designed belt conveyor with end pulley drives are included.

  8. Van Allen Discovery Most Important

    NASA Technical Reports Server (NTRS)

    Jastrow, R.

    1959-01-01

    The first step toward the exploration of space occurred approximately 22 months ago as a part of the International Geophysical Year. In the short interval since October, 1957, the new tools of research, the satellite and the space rocket, have produced two unexpected results of fundamental scientific importance. First, instruments placed in the Explorer satellites by James A. Van Allen have revealed the existence of layers of energetic particles in the outer atmosphere. This discovery constitutes the most significant research achievement of the IGY satellite program. The layers may provide the explanation for the aurora and other geophysical phenomena, and they will also influence the design of vehicles for manned space flight, whose occupants must be shielded against their harmful biological effects. Second, the shape of the earth has been determined very accurately with the aid of data from the first Vanguard. As a result of this investigation, we have found that our planet tends toward the shape of a pear, with its stem at the North Pole. This discovery may produce major changes in our ideas on the interior structure of the earth.

  9. Phosphine Catalysis of Allenes with Electrophiles

    PubMed Central

    Wang, Zhiming; Xu, Xingzhu; Kwon, Ohyun

    2014-01-01

    Nucleophilic phosphine catalysis of allenes with electrophiles is one of the most powerful and straightforward synthetic strategies for the generation of highly functionalized carbocycle or heterocycle structural motifs, which are present in a wide range of bioactive natural products and medicinally important substances. The reaction topologies can be controlled through judicious choice of the phosphine catalyst and the structural variations of starting materials. This Tutorial Review presents selected examples of nucleophilic phosphine catalysis using allenes and electrophiles. PMID:24663290

  10. Applications of radiation belt research

    NASA Astrophysics Data System (ADS)

    Lanzerotti, Louis J.

    2011-10-01

    When Arthur Clark and John Pierce proposed geosynchronous and low-Earth-orbiting (GEO and LEO) communications satellites, respectively, they did not envision that the environment in which their concepts would fly would be anything but benign. Discovery of the Van Allen radiation belts in 1958 fundamentally altered understanding of Earth's near-space environment and its impacts on technologies. Indeed, the first commercial telecommunications satellite, Telstar 1, in LEO, failed some 6 months after launch (10 July 1962) due to trapped radiation that had been enhanced from the Starfish Prime high-altitude nuclear test on the day prior to launch. Today radiation trapped in the geomagnetic field, as well as solar energetic particles that can access the magnetosphere, forms critical constraints on the design and operations of satellite systems. These considerations were important factors in the planning of the AGU Chapman Conference on radiation belts that was hosted in July 2011 by the Memorial University of Newfoundland in St. John's, Canada (see "Chapman Conference on Radiation Belts and the Inner Magnetosphere," page 4). The conference presentations, discussions, and hallway conversations illuminated current understanding of Earth's radiation belts and critical issues remaining. Certainly, fundamental understanding of radiation belt origins remains elusive. The relative roles of adiabatic processes, geomagnetic storm injections, and wave heating, among other considerations, are central topics of intense debate and of competing modeling regimes by numerous active groups.

  11. Using Jupiter's Synchrotron Radiation as a Probe into Jupiter's Inner Radiation Belts

    NASA Technical Reports Server (NTRS)

    Bolton, S. J.; Gulkis, S.; Klein, M. J.; Thorne, R. M.

    1995-01-01

    The Jovian decimetric emission is caused by the combined emission of synchrotron radiation originating from the relativistic electrons trapped in Jupiter's 'Van Allen radiation belts' and thermal emission from the planet's atmosphere. Synchrotron radiation characteristics and variations (which provides insight into the physical properties of Jupiter's inner radiation belts) will be amplified and discussed.

  12. Radiation Belt Storm Probe (RBSP) Mission

    NASA Technical Reports Server (NTRS)

    Sibeck, D. G.; Fox, N.; Grebowsky, J. M.; Mauk, B. H.

    2009-01-01

    Scheduled to launch in May 2012, NASA's dual spacecraft Living With a Star Radiation Belt Storm Probe mission carries the field and particle instrumentation needed to determine the processes that produce enhancements in radiation belt ion and electron fluxes, the dominant mechanisms that cause the loss of relativistic electrons, and the manner by which the ring current and other geomagnetic phenomena affect radiation belt behavior. The two spacecraft will operate in low-inclination elliptical lapping orbits around the Earth, within and immediately exterior to the Van Allen radiation belts. During course of their two year primary mission, they will cover the full range of local times, measuring both AC and DC electric and magnetic fields to 10kHz, as well as ions from 50 eV to 1 GeV and electrons with energies ranging from 50 eV to 10 MeV.

  13. Convection Electric Field Observations by THEMIS and the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Califf, S.; Li, X.; Bonnell, J. W.; Wygant, J. R.; Malaspina, D.; Hartinger, M.; Thaller, S. A.

    2013-12-01

    We present direct electric field measurements made by THEMIS and the Van Allen Probes in the inner magnetosphere, focusing on the large-scale, near-DC convection electric field. The convection electric field drives plasma Earthward from the tail into the inner magnetosphere, playing a critical role in forming the ring current. Although it is normally shielded deep inside the magnetosphere, during storm times this large-scale electric field can penetrate to low L values (L < 3), eroding the plasmasphere and also providing a mechanism for ~100 keV electron injection into the slot region and inner radiation belt. The relationship of the convection electric field with the plasmasphere is also important for understanding the dynamic outer radiation belt, as the plasmapause boundary has been strongly correlated with the dynamic variation of the outer radiation belt electrons.

  14. Inner Radiation Belt Dynamics and Climatology

    NASA Astrophysics Data System (ADS)

    Guild, T. B.; O'Brien, P. P.; Looper, M. D.

    2012-12-01

    We present preliminary results of inner belt proton data assimilation using an augmented version of the Selesnick et al. Inner Zone Model (SIZM). By varying modeled physics parameters and solar particle injection parameters to generate many ensembles of the inner belt, then optimizing the ensemble weights according to inner belt observations from SAMPEX/PET at LEO and HEO/DOS at high altitude, we obtain the best-fit state of the inner belt. We need to fully sample the range of solar proton injection sources among the ensemble members to ensure reasonable agreement between the model ensembles and observations. Once this is accomplished, we find the method is fairly robust. We will demonstrate the data assimilation by presenting an extended interval of solar proton injections and losses, illustrating how these short-term dynamics dominate long-term inner belt climatology.

  15. Electrophilic addition and cyclization reactions of allenes.

    PubMed

    Ma, Shengming

    2009-10-20

    Modern organic synthesis depends on the development of highly selective methods for the efficient construction of potentially useful target molecules. A primary goal in our laboratory is the discovery of new reactions that convert readily available starting materials to complex products with complete control of regio- and stereoselectivity. Allenes are one underused moiety in organic synthesis, because these groups are often thought to be highly reactive. However, many compounds containing the allene group, including natural products and pharmaceuticals, are fairly stable. The chemistry of allenes has been shown to have significant potential in organic synthesis. Electrophilic additions to allenes have often been considered to be synthetically less attractive due to the lack of efficient control of the regio- and stereoselectivity. However, this Account describes electrophilic reactions of allenes with defined regio- and stereoselectivity developed in our laboratory. Many substituted allenes are readily available from propargylic alcohols. Our work has involved an exploration of the reactions of these allenes with many different electrophiles: the E- or Z-halo- or seleno-hydroxylations of allenyl sulfoxides, sulfones, phosphine oxides, carboxylates, sulfides or selenides, butenolides, and arenes, and the halo- or selenolactonization reactions of allenoic acids and allenoates. These reactions have produced a host of new compounds such as stereodefined allylic alcohols, ethers, amides, thiiranes, and lactones. In all these reactions, water acts as a reactant and plays an important role in determining the reaction pathway and the stereoselectivity. The differing electronic properties of the two C=C bonds in these allenes determine the regioselectivity of these reactions. Through mechanistic studies of chirality transfer, isolation and reactivity of cyclic intermediates, (18)O-labeling, and substituent effects, we discovered that the E-stereoselectivity of some

  16. Van Allen Probe Charging During the St. Patrick's Day Event

    NASA Technical Reports Server (NTRS)

    Parker, L. Neergaard; Minow, J. I.

    2015-01-01

    The geomagnetic storms on and around March 17, 2015 marked the largest storms seen in the declining phase of the solar cycle to date. We use the Helium Oxygen Proton Electron (HOPE) mass spectrometer on board the Van Allen Probe - A and B satellites to study in detail the charging effects seen on these spacecraft during this time. Ion particle flux data provides information on the magnitude of the charging events using the ion line charging signature due to low energy ions accelerated by the spacecraft potential. Electron flux observations are used to correlate the charging environment with variations in spacecraft potential through the event. We also investigate the density and temperature of ions and electrons during the time of the charging event.

  17. Van Allen Probe Charging During the St. Patrick's Day Event

    NASA Astrophysics Data System (ADS)

    Parker, L. N.; Minow, J. I.

    2015-12-01

    The geomagnetic storms on and around March 17, 2015 marked the largest storms seen in the declining phase of the solar cycle to date. We use the Helium Oxygen Proton Electron (HOPE) mass spectrometer on board the Van Allen Probe - A and B satellites to study in detail the charging effects seen on these spacecraft during this time. Ion particle flux data provides information on the magnitude of the charging events using the ion line charging signature due to low energy ions accelerated by the spacecraft potential. Electron flux observations are used to correlate the charging environment with variations in spacecraft potential through the event. We also investigate the density and temperature of ions and electrons during the time of the charging event.

  18. Whistler-Mode Waves inside Density Ducts Observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Rosborough, S.; Bengtson, M.; Stein, R. L.; Streltsov, A. V.

    2015-12-01

    The Van Allen Probes satellites launched by NASA in 2012 are currently orbiting in Earth's radiation belts collecting data about electromagnetic waves and charged particles in the near-earth space environment. Whistler-mode waves are naturally occurring right-hand polarized, very-low frequency waves (< 30 kHz), that can efficiently interact with the energetic electrons in the earth's radiation belts magnetosphere and remediate them from the magnetosphere by precipitating these particles into the atmosphere. The important property of the whistler-mode waves is that they can be guided by density inhomogeneities extended along the ambient magnetic field and localized in the direction perpendicular to the field. Such density channels can be formed by the density enhancement or depletion and they are called ducts. The primary goal of our research is to find density duct and whistler waves in the data recorded by the Van Allen Probes satellites in the magnetosphere, and to reproduce these data with numerical simulations of time-dependent, two-dimensional electron MHD model. In this paper, we present results from our analysis of the observations performed by the Van Allen Probes satellites on 15 October 2014. Data from the probes show the electric and magnetic fields and plasma density. In this event whistler-mode waves were observed from 01:42 to 01:54 UT inside the localized density enhancement coincided with the flux of energetic electrons. Short time intervals, high concentrated electron density, and electron flux gradient activity make this event very interesting for the investigation. Numerical simulations of the electron MHD model revels reasonable quantitative agreement between numerical results and satellite observations, suggesting that the electromagnetic disturbances recorded by the Van Allen Probes satellites, are the whistler-mode waves indeed.

  19. NASA's RBSP-ECT Science Investigation of the Van Allen Probes Mission: Highlights of the Prime Mission Phase, Data Access Overview, and Opportunities to Collaborate in the Extended Mission Phase

    NASA Astrophysics Data System (ADS)

    Smith, S. S.; Friedel, R. H.; Larsen, B.; Reeves, G.; Spence, H. E.

    2015-12-01

    In this poster, we present a summary of access to the data products of the Radiation Belt Storm Probes - Energetic Particle Composition, and Thermal plasma (RBSP-ECT) suite of NASA's Van Allen Probes mission. The RBSP-ECT science investigation (http://rbsp-ect.sr.unh.edu) measures comprehensively the near-Earth charged particle environment in order to understand the processes that control the acceleration, global distribution, and variability of radiation belt electrons and ions. RBSP-ECT data products derive from the three instrument elements that comprise the suite, which collectively covers the broad energies that define the source and seed populations, the core radiation belts, and also their highest energy ultra-relativistic extensions. These RBSP-ECT instruments include, from lowest to highest energies: the Helium, Oxygen, Proton, and Electron (HOPE) sensor, the Magnetic Electron and Ion Spectrometer (MagEIS), and the Relativistic Electron and Proton Telescope (REPT). We provide a brief overview of their principles of operation, as well as a description of the Level 2-3 data products that the HOPE, MagEIS, and REPT instruments produce, both separately and together. We provide a summary of how to access these RBSP-ECT data products at our Science Operation Center and Science Data Center (http://www.rbsp-ect.lanl.gov/rbsp_ect.php ) as well as caveats for their use. Finally, in the spirit of efficiently and effectively promoting and encouraging new collaborations, we present a summary of past publications, current studies, and opportunities for your future participation in RBSP-ECT extended mission phase science.

  20. Allen Auditorium attic looking from southeast corner. Wine barrels with ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Allen Auditorium attic looking from southeast corner. Wine barrels with scrap used for counterweight material for lift up walls no longer in use - Sheldon Jackson College, Richard H. Allen Memorial Hall, Lincoln Street, Sitka, Sitka Borough, AK

  1. William G. Allen: On "Orators and Oratory."

    ERIC Educational Resources Information Center

    Calloway-Thomas, Carolyn

    1988-01-01

    William G. Allen was an African-American professor at Central College, McGrawville, New York. His lecture, "Orators and Oratory," delivered on June 22, 1852, is the earliest recorded study by an American Black on the ancient art of oratory. The text of the lecture is provided. (BJV)

  2. Observation of chorus waves by the Van Allen Probes: Dependence on solar wind parameters and scale size

    NASA Astrophysics Data System (ADS)

    Aryan, Homayon; Sibeck, David; Balikhin, Michael; Agapitov, Oleksiy; Kletzing, Craig

    2016-08-01

    Highly energetic electrons in the Earth's Van Allen radiation belts can cause serious damage to spacecraft electronic systems and affect the atmospheric composition if they precipitate into the upper atmosphere. Whistler mode chorus waves have attracted significant attention in recent decades for their crucial role in the acceleration and loss of energetic electrons that ultimately change the dynamics of the radiation belts. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity. However, geomagnetic indices are nonspecific parameters that are compiled from imperfectly covered ground based measurements. The present study uses wave data from the two Van Allen Probes to present the distribution of lower band chorus waves not only as functions of single geomagnetic index and solar wind parameters but also as functions of combined parameters. Also the current study takes advantage of the unique equatorial orbit of the Van Allen Probes to estimate the average scale size of chorus wave packets, during close separations between the two spacecraft, as a function of radial distance, magnetic latitude, and geomagnetic activity, respectively. Results show that the average scale size of chorus wave packets is approximately 1300-2300 km. The results also show that the inclusion of combined parameters can provide better representation of the chorus wave distributions in the inner magnetosphere and therefore can further improve our knowledge of the acceleration and loss of radiation belt electrons.

  3. Van Allen Probes observations of electromagnetic ion cyclotron waves triggered by enhanced solar wind dynamic pressure

    NASA Astrophysics Data System (ADS)

    Cho, J.-H.; Lee, D.-Y.; Noh, S.-J.; Shin, D.-K.; Hwang, J.; Kim, K.-C.; Lee, J. J.; Choi, C. R.; Thaller, S.; Skoug, R.

    2016-10-01

    Magnetospheric compression due to impact of enhanced solar wind dynamic pressure Pdyn has long been considered as one of the generation mechanisms of electromagnetic ion cyclotron (EMIC) waves. With the Van Allen Probe-A observations, we identify three EMIC wave events that are triggered by Pdyn enhancements under prolonged northward interplanetary magnetic field (IMF) quiet time preconditions. They are in contrast to one another in a few aspects. Event 1 occurs in the middle of continuously increasing Pdyn while Van Allen Probe-A is located outside the plasmapause at postmidnight and near the equator (magnetic latitude (MLAT) -3°). Event 2 occurs by a sharp Pdyn pulse impact while Van Allen Probe-A is located inside the plasmapause in the dawn sector and rather away from the equator (MLAT 12°). Event 3 is characterized by amplification of a preexisting EMIC wave by a sharp Pdyn pulse impact while Van Allen Probe-A is located outside the plasmapause at noon and rather away from the equator (MLAT -15°). These three events represent various situations where EMIC waves can be triggered by Pdyn increases. Several common features are also found among the three events. (i) The strongest wave is found just above the He+ gyrofrequency. (ii) The waves are nearly linearly polarized with a rather oblique propagation direction ( 28° to 39° on average). (iii) The proton fluxes increase in immediate response to the Pdyn impact, most significantly in tens of keV energy, corresponding to the proton resonant energy. (iv) The temperature anisotropy with T⊥ > T|| is seen in the resonant energy for all the events, although its increase by the Pdyn impact is not necessarily always significant. The last two points (iii) and (iv) may imply that in addition to the temperature anisotropy, the increase of the resonant protons must have played a critical role in triggering the EMIC waves by the enhanced Pdyn impact.

  4. Radiation belt dynamics during solar minimum

    SciTech Connect

    Gussenhoven, M.S.; Mullen, E.G. ); Holeman, E. )

    1989-12-01

    Two types of temporal variation in the radiation belts are studied using low altitude data taken onboard the DMSP F7 satellite: those associated with the solar cycle and those associated with large magnetic storm effects. Over a three-year period from 1984 to 1987 and encompassing solar minimum, the protons in the heart of the inner belt increased at a rate of approximately 6% per year. Over the same period, outer zone electron enhancements declined both in number and peak intensity. During the large magnetic storm of February 1986, following the period of peak ring current intensity, a second proton belt with energies up to 50 MeV was found at magnetic latitudes between 45{degrees} and 55{degrees}. The belt lasted for more than 100 days. The slot region between the inner and outer electron belts collapsed by the merging of the two populations and did not reform for 40 days.

  5. Inner Radiation Belt Data / Model Comparisons

    NASA Astrophysics Data System (ADS)

    Guild, Timothy; O'Brien, Paul; Selesnick, Richard

    We present detailed comparisons of a time-dependent inner radiation belt model with proton observations made by a variety of in-situ spacecraft during solar cycle 23. The recently-developed model (Selesnick et al., 2007) computes proton intensities as a function of time and of the three adiabatic invariants in the inner belt, which we convert to the observable count rate at the location of the satellite by using a nominal instrument response function. These comparisons and initial data-assimilation efforts suggest that the model performance can be improved especially during intervals containing unmodeled processes such as trapped proton losses during geomagnetic storms.

  6. Inner Radiation Belt Data / Model Comparisons

    NASA Astrophysics Data System (ADS)

    Guild, T. B.; O'Brien, T. P.; Selesnick, R.; Looper, M.

    2008-12-01

    We present detailed comparisons of a time-dependent inner radiation belt model with in-situ proton observations made by a variety of spacecraft during solar cycle 23. The recently-developed model (Selesnick et al., 2007) computes proton intensities as a function of time and of the three adiabatic invariants in the inner belt, which we convert to the observable count rate in a detector at the location of the satellite by using instrument response functions. These comparisons and initial data-assimilation efforts suggest that the model performance can be improved especially during injections of solar protons, and at L-shells above 2.

  7. EMIC wave scale size in the inner magnetosphere: Observations from the dual Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Blum, L. W.; Bonnell, J. W.; Agapitov, O.; Paulson, K.; Kletzing, C.

    2017-02-01

    Estimating the spatial scales of electromagnetic ion cyclotron (EMIC) waves is critical for quantifying their overall scattering efficiency and effects on thermal plasma, ring current, and radiation belt particles. Using measurements from the dual Van Allen Probes in 2013-2014, we characterize the spatial and temporal extents of regions of EMIC wave activity and how these depend on local time and radial distance within the inner magnetosphere. Observations are categorized into three types—waves observed by only one spacecraft, waves measured by both spacecraft simultaneously, and waves observed by both spacecraft with some time lag. Analysis reveals that dayside (and H+ band) EMIC waves more frequently span larger spatial areas, while nightside (and He+ band) waves are more often localized but can persist many hours. These investigations give insight into the nature of EMIC wave generation and support more accurate quantification of their effects on the ring current and outer radiation belt.

  8. Type II Isopentenyl Diphosphate Isomerase: Probing the Mechanism with Alkyne/Allene Diphosphate Substrate Analogues†

    PubMed Central

    Sharma, Nagendra K.; Pan, Jian-Jung; Poulter, C. Dale

    2010-01-01

    Isopentenyl diphosphate isomerase (IDI) catalyzes the interconversion of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the basic five-carbon building blocks of isoprenoid molecules. Two structurally unrelated classes of IDI are known. Type I IPP isomerase (IDI-1) utilizes a divalent metal in a protonation-deprotonation reaction. In contrast, the type II enzyme (IDI-2) requires reduced flavin, raising the possibility that the reaction catalyzed by IDI-2 involves the net addition/abstraction of a hydrogen atom. As part of our studies of the mechanism of isomerization for IDI-2, we synthesized allene and alkyne substrate analogues for the enzyme. These molecules are predicted to be substantially less reactive toward proton addition than IPP and DMAPP, but have similar reactivities toward hydrogen atom addition. This prediction was verified by calculations of gas phase heats of reaction for addition of a proton and of a hydrogen atom to 1-butyne (3) and 1,2-butadiene (4) to form the 1-buten-2-yl carbocation and radical, respectively, and related affinities for 2-methyl-1-butene (5) and 2-methyl-2-butene (6) using G3MP2B3 and CBS-QB3 protocols. Alkyne 1-OPP and allene 2-OPP were not substrates for Thermus thermophilus IDI-2 or Escherichia coli IDI-1, but instead were competitive inhibitors. The experimental and computational results are consistent with a protonation-deprotonation mechanism for the enzyme-catalyzed isomerization of IPP and DMAPP. PMID:20560533

  9. H. Julian Allen with Blunt Body Theory

    NASA Technical Reports Server (NTRS)

    1957-01-01

    H. Julian Allen is best known for his 'Blunt Body Theory' of aerodynamics, a design technique for alleviating the severe re-entry heating problem which was then delaying the development of ballistic missiles. His findings revolutionized the fundamental design of ballistic missle re-entry shapes. Subsequently, applied research led to applications of the 'blunt' shape to ballistic missles and spacecraft which were intended to re-enter the Earth's atmosphere. This application led to the design of ablative heat shields that protected the Mercury, Gemini and Apollo astronauts as their space capsules re- entered the Earth's atmosphere. 'Harvey' Allen as he was called by most, was not only a brilliant scientist and aeronautical engineer but was also admired for his kindness, thoughtfulness and sense of humor. Among his many other accomplishments, Harvey Allen served as Center Director of the NASA Ames Research Center from 1965 to 1969. He died of a heart attack on January 29, 1977 at the age of 66.

  10. EMIC Waves in the Radiation Belts

    NASA Astrophysics Data System (ADS)

    Usanova, M.; Mann, I. R.; Drozdov, A.; Orlova, K.; Shprits, Y.; Darrouzet, F.; Ergun, R.

    2014-12-01

    Electromagnetic ion cyclotron (EMIC) waves are believed to be important for influencing the dynamics of energetic particles in the inner magnetosphere - both ring current ions and radiation belt electrons - causing particle precipitation into the atmosphere. EMIC waves are generated from unstable ion distributions as a result of ion temperature anisotropy, with the ion dynamics being modified self-consistently by the growth of the EMIC instability. EMIC waves are also thought to influence higher energy electrons in the Van Allen belts through a Doppler shifted cyclotron resonance, including changes in electron pitch-angle distributions and electron scattering loss into the atmosphere. We will present some of the latest results addressing EMIC wave distribution, solar wind and magnetospheric conditions favorable for their generation and their role in energetic particle loss in the inner magnetosphere. We will focus on results from recent satellite missions including THEMIS and Cluster, as well as some of the latest results from the Van Allen Probes. We will also highlight the value of data from networks of modern ground-based magnetometers in providing continuous monitoring over global scales, especially in conjunction with in-situ measurements from satellites. Such coordinated ground-satellite conjunction studies represent a powerful tool for understanding the self-consistent and cross-energy coupling in the inner magnetosphere between ring current ions and radiation belt electrons via the intermediary of EMIC waves.

  11. Temperature of the plasmasphere from Van Allen Probes HOPE

    NASA Astrophysics Data System (ADS)

    Genestreti, K. J.; Goldstein, J.; Corley, G. D.; Farner, W.; Kistler, L. M.; Larsen, B. A.; Mouikis, C. G.; Ramnarace, C.; Skoug, R. M.; Turner, N. E.

    2017-01-01

    We introduce two novel techniques for estimating temperatures of very low energy space plasmas using, primarily, in situ data from an electrostatic analyzer mounted on a charged and moving spacecraft. The techniques are used to estimate proton temperatures during intervals where the bulk of the ion plasma is well below the energy bandpass of the analyzer. Both techniques assume that the plasma may be described by a one-dimensional E→×B→ drifting Maxwellian and that the potential field and motion of the spacecraft may be accounted for in the simplest possible manner, i.e., by a linear shift of coordinates. The first technique involves the application of a constrained theoretical fit to a measured distribution function. The second technique involves the comparison of total and partial-energy number densities. Both techniques are applied to Van Allen Probes Helium, Oxygen, Proton, and Electron (HOPE) observations of the proton component of the plasmasphere during two orbits on 15 January 2013. We find that the temperatures calculated from these two order-of-magnitude-type techniques are in good agreement with typical ranges of the plasmaspheric temperature calculated using retarding potential analyzer-based measurements - generally between 0.2 and 2 eV (2000-20,000 K). We also find that the temperature is correlated with L shell and hot plasma density and is negatively correlated with the cold plasma density. We posit that the latter of these three relationships may be indicative of collisional or wave-driven heating of the plasmasphere in the ring current overlap region. We note that these techniques may be easily applied to similar data sets or used for a variety of purposes.

  12. Observations and Simulations of Whistler-mode Waves Detected by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Bengtson, M.; Rosborough, S.; Stein, R. L.; Streltsov, A. V.; Matheny, M. M.

    2015-12-01

    In March of 2014, Van Allen Probe A observed several packets of whistler-mode waves while passing through the apogee of an orbit on the dayside magnetosphere. These waves were localized in regions of strong density inhomogeneity. For one observed wave, the wave maximum occurred within the center of the channel formed by a density enhancement. The other two waves were observed on either side of strong density depletion. We first determine the wave characteristics using data from Van Allen Probe A. Then, we use the observations to specify parameters in an electron MHD simulation to model the propagation of whistler-mode waves inside density structures. These observations and simulations demonstrate how whistler-mode waves can become trapped inside density structures, a phenomenon known as ducting. The density ducts serve to guide the whistler-mode waves into the earth's radiation belt while minimizing damping effects. The purpose of this research is to understand the role of density ducts in guiding whistler-mode waves, which will have important applications for remediation of energetic particles from the radiation belt.

  13. Rapid flattening of butterfly pitch angle distributions of radiation belt electrons by whistler-mode chorus

    NASA Astrophysics Data System (ADS)

    Yang, Chang; Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H. E.; Reeves, G. D.; Baker, D. N.; Blake, J. B.; Funsten, H. O.

    2016-08-01

    Van Allen radiation belt electrons exhibit complex dynamics during geomagnetically active periods. Investigation of electron pitch angle distributions (PADs) can provide important information on the dominant physical mechanisms controlling radiation belt behaviors. Here we report a storm time radiation belt event where energetic electron PADs changed from butterfly distributions to normal or flattop distributions within several hours. Van Allen Probes observations showed that the flattening of butterfly PADs was closely related to the occurrence of whistler-mode chorus waves. Two-dimensional quasi-linear STEERB simulations demonstrate that the observed chorus can resonantly accelerate the near-equatorially trapped electrons and rapidly flatten the corresponding electron butterfly PADs. These results provide a new insight on how chorus waves affect the dynamic evolution of radiation belt electrons.

  14. Allenes and computational chemistry: from bonding situations to reaction mechanisms.

    PubMed

    Soriano, Elena; Fernández, Israel

    2014-05-07

    The present review is focused on the application of computational/theoretical methods to the wide and rich chemistry of allenes. Special emphasis is made on the interplay and synergy between experimental and computational methodologies, rather than on recent developments in methods and algorithms. Therefore, this review covers the state-of-the-art applications of computational chemistry to understand and rationalize the bonding situation and vast reactivity of allenes. Thus, the contents of this review span from the most fundamental studies on the equilibrium structure and chirality of allenes to recent advances in the study of complex reaction mechanisms involving allene derivatives in organic and organometallic chemistry.

  15. Jupiter's radiation belts: Can Pioneer 10 survive?

    NASA Technical Reports Server (NTRS)

    Hess, W. N.; Birmingham, T. J.; Mead, G. D.

    1973-01-01

    Model calculations of Jupiter's electron and proton radiation belts indicate that the Galilean satellites can reduce particle fluxes in certain regions of the inner magnetosphere by as much as six orders of magnitude. Average fluxes should be reduced by a factor of 100 or more along the Pioneer 10 trajectory through the heart of Jupiter's radiation belts in early December. This may be enough to prevent serious radiation damage to the spacecraft.

  16. Jupiter's Radiation Belts: Can Pioneer 10 Survive?

    PubMed

    Hess, W N; Birmingham, T J; Mead, G D

    1973-12-07

    Model calculations of Jupiter's electron and proton radiation belts indicate that the Galilean satellites can reduce particle fluxes in certain regions of the inner magnetosphere by as much as six orders of magnitude. Average fluxes should be reduced by a factor of 100 or more along the Pioneer 10 trajectory through the heart of Jupiter's radiation belts in early December. This may be enough to prevent serious radiation damage to the spacecraft.

  17. Ion nose spectral structures observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Ferradas, C. P.; Zhang, J.-C.; Spence, H. E.; Kistler, L. M.; Larsen, B. A.; Reeves, G.; Skoug, R.; Funsten, H.

    2016-12-01

    We present a statistical study of nose-like structures observed in energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet. Nose structures are spectral features named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. Using 22 months of observations from the Helium Oxygen Proton Electron instrument onboard Van Allen Probe A, we determine the number of noses observed, and the minimum L shell reached and energy of each nose on each pass through the inner magnetosphere. We find that multiple noses occur more frequently in heavy ions than in H+ and are most often observed during quiet times. The heavy-ion noses penetrate to lower L shells than H+ noses, and there is an energy-magnetic local time (MLT) dependence in the nose locations and energies that is similar for all species. The observations are interpreted by using a steady state model of ion drift in the inner magnetosphere. The model is able to explain the energy and MLT dependence of the different types of nose structures. Different ion charge-exchange lifetimes are the main cause for the deeper penetration of heavy-ion noses. The species dependence and preferred geomagnetic conditions of multiple-nose events indicate that they must be on long drift paths, leading to strong charge-exchange effects. The results provide important insight into the spatial distribution, species dependence, and geomagnetic conditions under which nose structures occur.

  18. Spacecraft surface charging within geosynchronous orbit observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Sarno-Smith, Lois K.; Larsen, Brian A.; Skoug, Ruth M.; Liemohn, Michael W.; Breneman, Aaron; Wygant, John R.; Thomsen, Michelle F.

    2016-02-01

    Using the Helium Oxygen Proton Electron (HOPE) and Electric Field and Waves (EFW) instruments from the Van Allen Probes, we explored the relationship between electron energy fluxes in the eV and keV ranges and spacecraft surface charging. We present statistical results on spacecraft charging within geosynchronous orbit by L and MLT. An algorithm to extract the H+ charging line in the HOPE instrument data was developed to better explore intense charging events. Also, this study explored how spacecraft potential relates to electron number density, electron pressure, electron temperature, thermal electron current, and low-energy ion density between 1 and 210 eV. It is demonstrated that it is imperative to use both EFW potential measurements and the HOPE instrument ion charging line for examining times of extreme spacecraft charging of the Van Allen Probes. The results of this study show that elevated electron energy fluxes and high-electron pressures are present during times of spacecraft charging but these same conditions may also occur during noncharging times. We also show noneclipse significant negative charging events on the Van Allen Probes.

  19. Multi-Spacecraft Data Assimilation and Reanalysis During the THEMIS and Van Allen Probes Era

    NASA Astrophysics Data System (ADS)

    Kellerman, A. C.; Shprits, Y.; Kondrashov, D. A.; Podladchikova, T.; Drozdov, A.; Subbotin, D.

    2013-12-01

    consideration of the innovation vector may lead to a new physical understanding of the radiation belt system, which can later be used to improve our model forecasts. In the current study, we explore the radiation belt dynamics of the current era including data from the THEMIS, Van Allen Probes, GPS satellites, Akebono, NOAA and Cluster spacecraft. Intercalibration is performed between spacecraft on an individual energy channel basis, and in invariant coordinates. The global reanalysis allows an unprecedented analysis of the source-acceleration-transport-loss relationship in Earth's radiation belts. This analysis is used to refine our model capabilities, and to prepare the 3-D reanalysis for real-time data. The global 3-D reanalysis is an important step towards full-scale modeling and operational forecasting of this dynamic region of space.

  20. The role of EMIC waves in radiation belt dynamics

    NASA Astrophysics Data System (ADS)

    Usanova, Maria; Drozdov, Alexander; Mann, Ian; Orlova, Ksenia; Shprits, Yuri; Ergun, Robert

    2015-04-01

    Electromagnetic ion cyclotron (EMIC) waves are believed to be important for influencing the dynamics of relativistic electrons in the outer radiation belt through a Doppler shifted cyclotron resonance, including changes in electron pitch-angle distributions and electron scattering loss into the atmosphere. Theory predicts that regions of enhanced cold dense plasma density embedded in relatively low background magnetic field (such as the outer plasmasphere or plasmaspheric plumes) should aid EMIC wave growth. Also, enhanced plasma density lowers the energy threshold for electrons that can resonantly interact with EMIC waves down to less than 1 MeV and can be potentially important for loss of radiation belt electrons. However, so far there has been limited direct experimental evidence supporting this hypothesis. Our recent observations on the Van Allen Probes in conjunction with numerical modeling of electron pitch-angle distributions showed that EMIC waves do interact with radiation belt electrons, however this interaction is limited to very energetic (~ several MeV) particles and does not affect the core distribution. Up to this point, the relative importance of EMIC waves in the dynamics of the radiation belts remains unresolved and their properties, especially in the inner magnetosphere need further experimental and theoretical examination. In this talk, we will focus on these Van Allen Probes results and will address outstanding questions related to EMIC wave role in relativistic electron loss in the outer radiation belt.

  1. 33 CFR 80.1440 - Port Allen, Kauai, HI.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Port Allen, Kauai, HI. 80.1440 Section 80.1440 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Islands § 80.1440 Port Allen, Kauai, HI. A line drawn...

  2. 33 CFR 80.1440 - Port Allen, Kauai, HI.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Port Allen, Kauai, HI. 80.1440 Section 80.1440 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Islands § 80.1440 Port Allen, Kauai, HI. A line drawn...

  3. 33 CFR 80.1440 - Port Allen, Kauai, HI.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Port Allen, Kauai, HI. 80.1440 Section 80.1440 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Islands § 80.1440 Port Allen, Kauai, HI. A line drawn...

  4. 33 CFR 80.1440 - Port Allen, Kauai, HI.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Port Allen, Kauai, HI. 80.1440 Section 80.1440 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Islands § 80.1440 Port Allen, Kauai, HI. A line drawn...

  5. 33 CFR 80.1440 - Port Allen, Kauai, HI.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Port Allen, Kauai, HI. 80.1440 Section 80.1440 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Islands § 80.1440 Port Allen, Kauai, HI. A line drawn...

  6. Jupiters radiation belts and their effects on spacecraft

    NASA Technical Reports Server (NTRS)

    Parker, R. H.; Divita, E. L.; Gigas, G.

    1974-01-01

    The effects of electron and proton radiation on spacecraft which will operate in the trapped radiation belts of the planet Jupiter are described, and the techniques and results of the testing and simulation used in the radiation effects program are discussed. Available data from the Pioneer 10 encounter of Jupiter are compared with pre-encounter models of the Jupiter radiation belts. The implications that the measured Jovian radiation belts have for future missions are considered.

  7. Allenes in Asymmetric Catalysis. Asymmetric Ring-Opening of Meso-Epoxides Catalyzed by Allene-Containing Phosphine Oxides

    PubMed Central

    Pu, Xiaotao; Qi, Xiangbing; Ready, Joseph M.

    2009-01-01

    Unsymmetrically substituted allenes (1,2 dienes) are inherently chiral and can be prepared in optically pure form. Nonetheless, to date the allene framework has not been incorporated into ligands for asymmetric catalysis. Since allenes project functionality differently than either tetrahedral carbon or chiral biaryls, they may create complementary chiral environments. This study demonstrates that optically active C2 symmetric allene-containing bisphosphine oxides can catalyze the addition of SiCl4 to meso epoxides with high enantioselectivity. The epoxide-opening likely involves generation of a Lewis acidic, cationic (bisphosphine oxide)SiCl3 complex. The fact that high asymmetric induction is observed suggests that allenes may represent a new platform for the development of ligands and catalysts for asymmetric synthesis. PMID:19722613

  8. Monte Carlo simulations of soft proton flares: testing the physics with XMM-Newton

    NASA Astrophysics Data System (ADS)

    Fioretti, Valentina; Bulgarelli, Andrea; Malaguti, Giuseppe; Spiga, Daniele; Tiengo, Andrea

    2016-07-01

    Low energy protons (< 100 - 300 keV) in the Van Allen belt and the outer regions can enter the field of view of X-ray focusing telescopes, interact with the Wolter-I optics, and reach the focal plane. The funneling of soft protons was discovered after the damaging of the Chandra/ACIS Front-Illuminated CCDs in September 1999 after the first passages through the radiation belt. The use of special filters protects the XMM-Newton focal plane below an altitude of 70000 km, but above this limit the effect of soft protons is still present in the form of sudden ares in the count rate of the EPIC instruments that can last from hundreds of seconds to hours and can hardly be disentangled from X-ray photons, causing the loss of large amounts of observing time. The accurate characterization of (i) the distribution of the soft proton population, (ii) the physics interaction at play, and (iii) the effect on the focal plane, are mandatory to evaluate the background and design the proton magnetic diverter on board future X-ray focusing telescopes (e.g. ATHENA). Several solutions have been proposed so far for the primary population and the physics interaction, however the difficulty in precise angle and energy measurements in laboratory makes the smoking gun still unclear. Since the only real data available is the XMM-Newton spectrum of soft proton flares in orbit, we try to characterize the input proton population and the physics interaction by simulating, using the BoGEMMS framework, the proton interaction with a simplified model of the X-ray mirror module and the focal plane, and comparing the result with a real observation. The analysis of ten orbits of observations of the EPIC/pn instrument show that the detection of flares in regions far outside the radiation belt is largely influenced by the different orientation of the Earth's magnetosphere respect with XMM-Newton'os orbit, confirming the solar origin of the soft proton population. The Equator-S proton spectrum at 70000 km

  9. Variation of the ion composition in the ring current during magnetic storms: Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Luo, Hao; Du, Aimin; Ge, Yasong; Cao, Xin; Zhang, Ying; Wang, Yuan

    2015-04-01

    It has been reported that the energy density of the oxygen ions in the ring current region will show more enhancements than protons during magnetic storms. Knowing how the ion composition changes during a magnetic storm is important for understanding the dynamic processes in the inner magnetosphere. By using ion flux data from HOPE and RBSPICE instruments on board the Van Allen probes, we study the energy density variation of both protons and oxygen ions during fifteen strong magnetic storms (minimum Dst < -80 nT) happened during year 2013 to 2014. Results provide important details about the ion composition at different storm stages and different magnetic local times. Results also give important indications about the ion acceleration in the inner magnetosphere and the source of the ring current ions during the magnetic storms.

  10. Laterally bendable belt conveyor

    DOEpatents

    Peterson, William J.

    1985-01-01

    An endless, laterally flexible and bendable belt conveyor particularly adapted for coal mining applications in facilitating the transport of the extracted coal up- or downslope and around corners in a continuous manner is disclosed. The conveying means includes a flat rubber belt reinforced along the middle portion thereof along which the major portion of the belt tension is directed so as to cause rotation of the tubular shaped belt when trammed around lateral turns thus preventing excessive belt bulging distortion between adjacent belt supports which would inhibit belt transport. Pretension induced into the fabric reinforced flat rubber belt by conventional belt take-up means supports the load conveyed when the belt conveyor is making lateral turns. The carrying and return portions of the belt are supported and formed into a tubular shape by a plurality of shapers positioned along its length. Each shaper is supported from above by a monorail and includes clusters of idler rollers which support the belt. Additional cluster rollers in each shaper permit the belt supporting roller clusters to rotate in response to the belt's operating tension imposed upon the cluster rollers by induced lateral belt friction forces. The freely rotating roller clusters thus permit the belt to twist on lateral curves without damage to itself while precluding escape of the conveyed material by effectively enclosing it in the tube-shaped, inner belt transport length.

  11. Optimization of measurements of the Earth's radiation belt particle fluxes

    NASA Astrophysics Data System (ADS)

    Panasyuk, M. I.; Podzolko, M. V.; Kovtyukh, A. S.; Brilkov, I. A.; Vlasova, N. A.; Kalegaev, V. V.; Osedlo, V. I.; Tulupov, V. I.; Yashin, I. V.

    2017-03-01

    The Earth's radiation belts discovered at the end of the 1950s have great scientific and practical interest. Their main characteristics in magnetically quiet periods are well known. However, the dynamics of the Earth's radiation belts during magnetic storms and substorms, particularly the dynamics of relativistic electrons of the outer belt, when Earth's radiation belt particle fluxes undergo significant time variations, is studied insufficiently. At present, principally new experiments have been performed and planned with the intention to better study the dynamics of the Earth's radiation belts and to operationally control the space-energy distributions of the Earth's radiation belt particle fluxes. In this paper, for spacecraft designed to measure the fluxes of electrons and protons of the Earth's radiation belts at altitudes of 0.5-10000 km, the optimal versions for detector orientation and orbital parameters have been considered and selected.

  12. Statistical distribution of EMIC wave spectra: Observations from Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Zhang, X.-J.; Li, W.; Thorne, R. M.; Angelopoulos, V.; Bortnik, J.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.

    2016-12-01

    It has been known that electromagnetic ion cyclotron (EMIC) waves can precipitate ultrarelativistic electrons through cyclotron resonant scattering. However, the overall effectiveness of this mechanism has yet to be quantified, because it is difficult to obtain the global distribution of EMIC waves that usually exhibit limited spatial presence. We construct a statistical distribution of EMIC wave frequency spectra and their intensities based on Van Allen Probes measurements from September 2012 to December 2015. Our results show that as the ratio of plasma frequency over electron gyrofrequency increases, EMIC wave power becomes progressively dominated by the helium band. There is a pronounced dawn-dusk asymmetry in the wave amplitude and the frequency spectrum. The frequency spectrum does not follow the commonly used single-peak Gaussian function. Incorporating these realistic EMIC wave frequency spectra into radiation belt models is expected to improve the quantification of EMIC wave scattering effects in ultrarelativistic electron dynamics.

  13. Van Allen Probes observations of oxygen cyclotron harmonic waves in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Usanova, M. E.; Malaspina, D. M.; Jaynes, A. N.; Bruder, R. J.; Mann, I. R.; Wygant, J. R.; Ergun, R. E.

    2016-09-01

    Waves with frequencies in the vicinity of the oxygen cyclotron frequency and its harmonics have been regularly observed on the Van Allen Probes satellites during geomagnetic storms. We focus on properties of these waves and present events from the main phase of two storms on 1 November 2012 and 17 March 2013 and associated dropouts of a few MeV electron fluxes. They are electromagnetic, in the frequency range ~0.5 to several Hz, and amplitude ~0.1 to a few nT in magnetic and ~0.1 to a few mV/m in electric field, with both the wave velocity and the Poynting vector directed almost parallel to the background magnetic field. These properties are very similar to those of electromagnetic ion cyclotron waves, which are believed to contribute to loss of ring current ions and radiation belt electrons and therefore can be also important for inner magnetosphere dynamics.

  14. Ion nose spectral structures observed by the Van Allen Probes

    DOE PAGES

    Ferradas, C. P.; Zhang, J. -C.; Spence, H. E.; ...

    2016-11-22

    Here, we present a statistical study of nose-like structures observed in energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet. Nose structures are spectral features named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. Using 22 months of observations from the Helium Oxygen Proton Electron (HOPE) instrument onboard Van Allen Probe A, we determine the number of noses observed, and the minimum L-shell reached and energy of each nose on each pass through the inner magnetosphere. We find that multiple noses occur more frequentlymore » in heavy ions than in H+, and are most often observed during quiet times. The heavy-ion noses penetrate to lower L shells than H+ noses and there is an energy-magnetic local time (MLT) dependence in the nose locations and energies that is similar for all species. The observations are interpreted using a steady-state model of ion drift in the inner magnetosphere. The model is able to explain the energy and MLT dependence of the different types of nose structures. Different ion charge exchange lifetimes are the main cause for the deeper penetration of heavy-ion noses. The species dependence and preferred geomagnetic conditions of multiple-nose events indicate that they must be on long drift paths, leading to strong charge-exchange effects. The results provide important insight into the spatial distribution, species dependence, and geomagnetic conditions under which nose structures occur.« less

  15. Ion nose spectral structures observed by the Van Allen Probes

    SciTech Connect

    Ferradas, C. P.; Zhang, J. -C.; Spence, H. E.; Kistler, L. M.; Larsen, Brian Arthur; Reeves, Geoffrey D.; Skoug, Ruth M.; Funsten, Herbert O.

    2016-11-22

    Here, we present a statistical study of nose-like structures observed in energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet. Nose structures are spectral features named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. Using 22 months of observations from the Helium Oxygen Proton Electron (HOPE) instrument onboard Van Allen Probe A, we determine the number of noses observed, and the minimum L-shell reached and energy of each nose on each pass through the inner magnetosphere. We find that multiple noses occur more frequently in heavy ions than in H+, and are most often observed during quiet times. The heavy-ion noses penetrate to lower L shells than H+ noses and there is an energy-magnetic local time (MLT) dependence in the nose locations and energies that is similar for all species. The observations are interpreted using a steady-state model of ion drift in the inner magnetosphere. The model is able to explain the energy and MLT dependence of the different types of nose structures. Different ion charge exchange lifetimes are the main cause for the deeper penetration of heavy-ion noses. The species dependence and preferred geomagnetic conditions of multiple-nose events indicate that they must be on long drift paths, leading to strong charge-exchange effects. The results provide important insight into the spatial distribution, species dependence, and geomagnetic conditions under which nose structures occur.

  16. Belt attachment and system

    DOEpatents

    Schneider, Abraham D.; Davidson, Erick M.

    2016-02-02

    Disclosed herein is a belt assembly including a flexible belt with an improved belt attachment. The belt attachment includes two crossbars spaced along the length of the belt. The crossbars retain bearings that allow predetermined movement in six degrees of freedom. The crossbars are connected by a rigid body that attaches to the bearings. Implements that are attached to the rigid body are simply supported but restrained in pitching rotation.

  17. Electron-proton spectrometer

    NASA Technical Reports Server (NTRS)

    Winckler, J. R.

    1973-01-01

    An electron-proton spectrometer was designed to measure the geomagnetically trapped radiation in a geostationary orbit at 6.6 earth radii in the outer radiation belt. This instrument is to be flown on the Applications Technology Satellite-F (ATS-F). The electron-proton spectrometer consists of two permanent magnet surface barrier detector arrays and associated electronics capable of selecting and detecting electrons in three energy ranges: (1) 30-50 keV, (2) 150-200 keV, and (3) 500 keV and protons in three energy ranges. The electron-proton spectrometer has the capability of measuring the fluxes of electrons and protons in various directions with respect to the magnetic field lines running through the satellite. One magnet detector array system is implemented to scan between EME north and south through west, sampling the directional flux in 15 steps. The other magnet-detector array system is fixed looking toward EME east.

  18. Historic American Buildings Survey Harold Allen, Photographer, June, 1964 VIEW: ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Historic American Buildings Survey Harold Allen, Photographer, June, 1964 VIEW: EXTERIOR: WEST (CLARK STREET) AND SOUTH (JACKSON BLVD.) SIDES - U.S. Post Office, Customs House & Sub-Treasury, 218 South Dearborn Street, Chicago, Cook County, IL

  19. 8. Historic American Buildings Survey Harold Allen, Photographer 24 June ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. Historic American Buildings Survey Harold Allen, Photographer 24 June 1964 GRAND STAIRWAY, FROM SECOND FLOOR HALL, SHOWING STAINED GLASS WINDOW IN WEST WALL ABOVE LANDING - Francis J. Dewes House, 503 West Wrightwood Avenue, Chicago, Cook County, IL

  20. 6. Historic American Buildings Survey Harold Allen, Photographer June 1964 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Historic American Buildings Survey Harold Allen, Photographer June 1964 STAINED GLASS WINDOW, WEST WINDOW IN SOUTH WALL, FROM BALCONY - Kehilath Anshe Ma'ariv Synagogue, 3301 South Indiana Avenue, Chicago, Cook County, IL

  1. 1. Historic American Buildings Survey Harold Allen, Photographer 24 May ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Historic American Buildings Survey Harold Allen, Photographer 24 May 1964 (R. TO L.) MANHATTAN BLDG. (WEST FRONT AND SOUTH SIDES), OLD COLONY BLDG., FISHER BLDG., MONADNOCK BLOCK - Manhattan Building, 431 South Dearborn Street, Chicago, Cook County, IL

  2. Substituent effects on dynamics at conical intersections: Allene and methyl allenes

    NASA Astrophysics Data System (ADS)

    Neville, Simon P.; Wang, Yanmei; Boguslavskiy, Andrey E.; Stolow, Albert; Schuurman, Michael S.

    2016-01-01

    We report a joint experimental and theoretical study on the ultrafast excited state dynamics of allene and a series of its methylated analogues (1,2-butadiene, 1,1-dimethylallene, and tetramethylallene) in order to elucidate the conical intersection mediated dynamics that give rise to ultrafast relaxation to the ground electronic state. We use femtosecond time-resolved photoelectron spectroscopy (TRPES) to probe the coupled electronic-vibrational dynamics following UV excitation at 200 nm (6.2 eV). Ab initio multiple spawning (AIMS) simulations are employed to determine the mechanistic details of two competing dynamical pathways to the ground electronic state. In all molecules, these pathways are found to involve as follows: (i) twisting about the central allenic C-C-C axis followed by pyramidalization at one of the terminal carbon atoms and (ii) bending of allene moiety. Importantly, the AIMS trajectory data were used for ab initio simulations of the TRPES, permitting direct comparison with experiment. For each molecule, the decay of the TRPES signal is characterized by short (30 fs, 52 fs, 23 fs) and long (1.8 ps, 3.5 ps, [306 fs, 18 ps]) time constants for 1,2-butadiene, 1,1-dimethylallene, and tetramethylallene, respectively. However, AIMS simulations show that these time constants are only loosely related to the evolution of electronic character and actually more closely correlate to large amplitude motions on the electronic excited state, modulating the instantaneous vertical ionization potentials. Furthermore, the fully substituted tetramethylallene is observed to undergo qualitatively different dynamics, as displacements involving the relatively massive methyl groups impede direct access to the conical intersections which give rise to the ultrafast relaxation dynamics observed in the other species. These results show that the branching between the "twisting" and "bending" pathways can be modified via the selective methylation of the terminal carbon atoms of

  3. Substituent effects on dynamics at conical intersections: Allene and methyl allenes.

    PubMed

    Neville, Simon P; Wang, Yanmei; Boguslavskiy, Andrey E; Stolow, Albert; Schuurman, Michael S

    2016-01-07

    We report a joint experimental and theoretical study on the ultrafast excited state dynamics of allene and a series of its methylated analogues (1,2-butadiene, 1,1-dimethylallene, and tetramethylallene) in order to elucidate the conical intersection mediated dynamics that give rise to ultrafast relaxation to the ground electronic state. We use femtosecond time-resolved photoelectron spectroscopy (TRPES) to probe the coupled electronic-vibrational dynamics following UV excitation at 200 nm (6.2 eV). Ab initio multiple spawning (AIMS) simulations are employed to determine the mechanistic details of two competing dynamical pathways to the ground electronic state. In all molecules, these pathways are found to involve as follows: (i) twisting about the central allenic C-C-C axis followed by pyramidalization at one of the terminal carbon atoms and (ii) bending of allene moiety. Importantly, the AIMS trajectory data were used for ab initio simulations of the TRPES, permitting direct comparison with experiment. For each molecule, the decay of the TRPES signal is characterized by short (30 fs, 52 fs, 23 fs) and long (1.8 ps, 3.5 ps, [306 fs, 18 ps]) time constants for 1,2-butadiene, 1,1-dimethylallene, and tetramethylallene, respectively. However, AIMS simulations show that these time constants are only loosely related to the evolution of electronic character and actually more closely correlate to large amplitude motions on the electronic excited state, modulating the instantaneous vertical ionization potentials. Furthermore, the fully substituted tetramethylallene is observed to undergo qualitatively different dynamics, as displacements involving the relatively massive methyl groups impede direct access to the conical intersections which give rise to the ultrafast relaxation dynamics observed in the other species. These results show that the branching between the "twisting" and "bending" pathways can be modified via the selective methylation of the terminal carbon atoms of

  4. Substituent effects on dynamics at conical intersections: Allene and methyl allenes

    SciTech Connect

    Neville, Simon P.; Wang, Yanmei; Boguslavskiy, Andrey E.; Stolow, Albert; Schuurman, Michael S.

    2016-01-07

    We report a joint experimental and theoretical study on the ultrafast excited state dynamics of allene and a series of its methylated analogues (1,2-butadiene, 1,1-dimethylallene, and tetramethylallene) in order to elucidate the conical intersection mediated dynamics that give rise to ultrafast relaxation to the ground electronic state. We use femtosecond time-resolved photoelectron spectroscopy (TRPES) to probe the coupled electronic-vibrational dynamics following UV excitation at 200 nm (6.2 eV). Ab initio multiple spawning (AIMS) simulations are employed to determine the mechanistic details of two competing dynamical pathways to the ground electronic state. In all molecules, these pathways are found to involve as follows: (i) twisting about the central allenic C–C–C axis followed by pyramidalization at one of the terminal carbon atoms and (ii) bending of allene moiety. Importantly, the AIMS trajectory data were used for ab initio simulations of the TRPES, permitting direct comparison with experiment. For each molecule, the decay of the TRPES signal is characterized by short (30 fs, 52 fs, 23 fs) and long (1.8 ps, 3.5 ps, [306 fs, 18 ps]) time constants for 1,2-butadiene, 1,1-dimethylallene, and tetramethylallene, respectively. However, AIMS simulations show that these time constants are only loosely related to the evolution of electronic character and actually more closely correlate to large amplitude motions on the electronic excited state, modulating the instantaneous vertical ionization potentials. Furthermore, the fully substituted tetramethylallene is observed to undergo qualitatively different dynamics, as displacements involving the relatively massive methyl groups impede direct access to the conical intersections which give rise to the ultrafast relaxation dynamics observed in the other species. These results show that the branching between the “twisting” and “bending” pathways can be modified via the selective methylation of the terminal

  5. Regiodivergent and Stereoselective Hydrosilylation of 1,3-Disubstituted Allenes.

    PubMed

    Miller, Zachary D; Dorel, Ruth; Montgomery, John

    2015-07-27

    Methods for the highly stereoselective and regiodivergent hydrosilylation of 1,3-disubstituted allenes have been developed. The synthesis of E allylsilanes is accomplished with palladium NHC catalysts, and trisubstituted Z alkenylsilanes are accessed with nickel NHC catalysts. Unsymmetrically substituted allenes are well tolerated with nickel catalysis and afford Z alkenylsilanes. Evidence for a plausible mechanism was obtained through an isotopic double-labeling crossover study.

  6. Reactivity and Chemoselectivity of Allenes in Rh(I)-Catalyzed Intermolecular (5 + 2) Cycloadditions with Vinylcyclopropanes: Allene-Mediated Rhodacycle Formation Can Poison Rh(I)-Catalyzed Cycloadditions

    PubMed Central

    2015-01-01

    Allenes are important 2π building blocks in organic synthesis and engage as 2-carbon components in many metal-catalyzed reactions. Wender and co-workers discovered that methyl substituents on the terminal allene double bond counterintuitively change the reactivities of allenes in [Rh(CO)2Cl]2-catalyzed intermolecular (5 + 2) cycloadditions with vinylcyclopropanes (VCPs). More sterically encumbered allenes afford higher cycloadduct yields, and such effects are also observed in other Rh(I)-catalyzed intermolecular cycloadditions. Through density functional theory calculations (B3LYP and M06) and experiment, we explored this enigmatic reactivity and selectivity of allenes in [Rh(CO)2Cl]2-catalyzed intermolecular (5 + 2) cycloadditions with VCPs. The apparent low reactivity of terminally unsubstituted allenes is associated with a competing allene dimerization that irreversibly sequesters rhodium. With terminally substituted allenes, steric repulsion between the terminal substituents significantly increases the barrier of allene dimerization while the barrier of the (5 + 2) cycloaddition is not affected, and thus the cycloaddition prevails. Computation has also revealed the origin of chemoselectivity in (5 + 2) cycloadditions with allene-ynes. Although simple allene and acetylene have similar reaction barriers, intermolecular (5 + 2) cycloadditions of allene-ynes occur exclusively at the terminal allene double bond. The terminal double bond is more reactive due to the enhanced d−π* backdonation. At the same time, insertion of the internal double bond of an allene-yne has a higher barrier as it would break π conjugation. Substituted alkynes are more difficult to insert compared with acetylene, because of the steric repulsion from the additional substituents. This leads to the greater reactivity of the allene double bond relative to the alkynyl group in allene-ynes. PMID:25379606

  7. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons

    SciTech Connect

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q. -G.; Zhou, X. -Z.; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y. -X.; Gao, Zhonglei; He, Zhaoguo; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Blake, J. B.; Wygant, J. R.

    2015-12-22

    The Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. So, our results demonstrate that the ULF waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons.

  8. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons

    DOE PAGES

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; ...

    2015-12-22

    The Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. So, our results demonstrate that the ULFmore » waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons.« less

  9. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons

    PubMed Central

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q.-G.; Zhou, X.-Z.; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y.-X.; Gao, Zhonglei; He, Zhaoguo; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Blake, J. B.; Wygant, J. R.

    2015-01-01

    Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. Our results demonstrate that the ULF waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons. PMID:26690250

  10. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons.

    PubMed

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q-G; Zhou, X-Z; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y-X; Gao, Zhonglei; He, Zhaoguo; Baker, D N; Spence, H E; Reeves, G D; Blake, J B; Wygant, J R

    2015-12-22

    Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. Our results demonstrate that the ULF waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons.

  11. Combined Effect of EMIC Waves and Magnetosonic Waves on Rapid Loss of MeV Electrons in Outer Radiation Belt

    NASA Astrophysics Data System (ADS)

    Xiong, Y.; Chen, L.; Xie, L.; Pu, Z.

    2015-12-01

    Electromagnetic ion cyclotron (EMIC) waves can cause rapid loss of relativistic electrons in the outer radiation belt by pitch angle scattering, especially for >2 MeV electrons. The rapid pitch angle scattering is limited to the low pitch angle electrons and cannot affect ~90 degree electrons. However, normal pitch angle distribution (PAD) of electron flux with peaks at 90 degree pitch angle is generally observed in the outer radiation belt. Magnetosonic (MS) waves in the outer radiation belt can scatter ~90 degree pitch angle electrons to lower pitch angles and lead to the formation of electron's butterfly PAD. This paper studies the combined effect of EMIC waves and MS waves on the loss of the outer belt relativistic electrons during a minor storm on 16 November 2013 by combining Van Allen Probe measurements with test particle simulations. During the pre-storm period strong MS waves were observed by Probe A. Meanwhile normal PAD of 2.1 MeV electrons was measured by relativistic electron and proton telescope (REPT) on Probe A. When Probe B orbit was passing through the same area during the storm main phase, MS waves still existed but with weak intensity, while strong EMIC wave with ~1 nT amplitude were observed. Butterfly pitch angle distribution of 2.1 MeV electrons was seen to be formed at L = ~5-6. Four hours later, stronger EMIC waves were measured by Probe A and the fluxes of 2.1 MeV electrons at L=~5-6 showed great losses at all pitch angle sectors. The computed pitch angle diffusion rates show that the MS waves can produce the observed butterfly pitch angle distributions (flux peaks at 50-60 degree) for 2.1 MeV electrons. This indicates that ~90 degree pitch angle electrons are scattered to lower pitch angle by MS waves to form the butterfly PAD, and the observed strong EMIC waves then can resonate effectively with these butterfly distributed electrons and cause the electron loss in ~hours. Therefore, we suggest that although MS waves themselves cannot

  12. Observations and Simulations of Whistler Waves in Earth's Radiation Belts

    NASA Astrophysics Data System (ADS)

    Stein, R. L.; Bengtson, M.; Rosborough, S.; Streltsov, A. V.

    2015-12-01

    In late 2014, a cluster of whistler waves localized within prominent density enhancements was observed by the Van Allen Probes in the nightside magnetosphere. The most powerful waves lasted approximately thirteen minutes, occurred thirty minutes apart, and were accompanied by increased particle acceleration throughout the region. In order to properly simulate the waves we first establish their characteristics using data from the Van Allen Probes, primarily from the EMFISIS instrument. Next, we incorporate the conditions and location in which the waves occurred into a mathematical model, that in turn is used to provide an accurate simulation. Such simulations will allow a closer and more analytical study of how whistler waves become trapped in density ducts. This research will also advance our understanding of how we can use these waves to remove energetic particles from Earth's radiation belts.

  13. Inner Magnetosphere keV Ion Drift Path Boundaries as Observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Strangeway, R. J.; Zhang, J.; Larsen, B.

    2014-12-01

    The drifts of keV ions in the inner magnetosphere are controlled by both electric field drifts and gradient and curvature (i.e., magnetic field) drifts, and further the magnetic field drifts oppose the corotation electric field drift in the dusk local time sector. Consequently, the ion drift paths can be quite complicated with the medium-energy ions drifting close to the Earth, but still being on open drift paths. In addition, structure in the energy-time spectrograms can be a consequence of either particle injection or particle loss. In order to distinguish between the two we will compare the energy-time spectrograms acquired with the Helium Oxygen Proton Electron (HOPE) mass spectrometer on board the Van Allen Probes with predictions of drift path boundaries. The simplest model assumes a uniform convection electric field and dipole model field, and we will use this a starting point for the comparison. The model can be modified to include shielding of the convection electric field, and rotation in local time of the zero-energy dusk-side stagnation point. As an additional check of the model we will compare the electric field used in the model with the electric field as measured by the Van Allen Probes, as well as the validity of using a dipole magnetic field through comparison with the measured magnetic field.

  14. Void structure of O+ ions in the inner magnetosphere observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Nakayama, Y.; Ebihara, Y.; Ohtani, S.; Gkioulidou, M.; Takahashi, K.; Kistler, L. M.; Tanaka, T.

    2016-12-01

    The Van Allen Probes Helium Oxygen Proton Electron instrument observed a new type of enhancement of O+ ions in the inner magnetosphere during substorms. As the satellite moved outward in the premidnight sector, the flux of the O+ ions with energy 10 keV appeared first in the energy-time spectrograms. Then, the enhancement of the flux spread toward high and low energies. The enhanced flux of the O+ ions with the highest energy remained, whereas the flux of the ions with lower energy vanished near apogee, forming what we call the void structure. The structure cannot be found in the H+ spectrogram. We studied the generation mechanism of this structure by using numerical simulation. We traced the trajectories of O+ ions in the electric and magnetic fields from the global magnetohydrodynamics simulation and calculated the flux of O+ ions in the inner magnetosphere in accordance with the Liouville theorem. The simulated spectrograms are well consistent with the ones observed by Van Allen Probes. We suggest the following processes. (1) When magnetic reconnection starts, an intensive equatorward and tailward plasma flow appears in the plasma lobe. (2) The flow transports plasma from the lobe to the plasma sheet where the radius of curvature of the magnetic field line is small. (3) The intensive dawn-dusk electric field transports the O+ ions earthward and accelerates them nonadiabatically to an energy threshold; (4) the void structure appears at energies below the threshold.

  15. Synaptic ribbon. Conveyor belt or safety belt?

    PubMed

    Parsons, T D; Sterling, P

    2003-02-06

    The synaptic ribbon in neurons that release transmitter via graded potentials has been considered as a conveyor belt that actively moves vesicles toward their release sites. But evidence has accumulated to the contrary, and it now seems plausible that the ribbon serves instead as a safety belt to tether vesicles stably in mutual contact and thus facilitate multivesicular release by compound exocytosis.

  16. Unraveling the drivers of the storm time radiation belt response

    NASA Astrophysics Data System (ADS)

    Kilpua, E. K. J.; Hietala, H.; Turner, D. L.; Koskinen, H. E. J.; Pulkkinen, T. I.; Rodriguez, J. V.; Reeves, G. D.; Claudepierre, S. G.; Spence, H. E.

    2015-05-01

    We present a new framework to study the time evolution and dynamics of the outer Van Allen belt electron fluxes. The framework is entirely based on the large-scale solar wind storm drivers and their substructures. The Van Allen Probe observations, revealing the electron flux behavior throughout the outer belt, are combined with continuous, long-term (over 1.5 solar cycles) geosynchronous orbit data set from GOES and solar wind measurements A superposed epoch analysis, where we normalize the timescales for each substructure (sheath, ejecta, and interface region) allows us to avoid smearing effects and to distinguish the electron flux evolution during various driver structures. We show that the radiation belt response is not random: The electron flux variations are determined by the combined effect of the structured solar wind driver and prestorm electron flux levels. In particular, we find that loss mechanisms dominate during stream interface regions, coronal mass ejection (CME) ejecta, and sheaths while enhancements occur during fast streams trailing the stream interface or the CME.

  17. Shield Optimization Program, Part 2: Effects of Van Allen Belt Radiation on SDI Weapon Platforms

    DTIC Science & Technology

    1988-12-01

    104 KV2 109 -110 -111 KV2 110 -111 KV2 111 KV2 112 -108 KV3 113 -114 KV3 114 KV3 115 -113 -116 KV3 116 KV3 117 -115 -118 KV3 118 KV3 119 -117...120 KV3 120 -121 -122 KV3 121 -122 KV3 122 -123 KV3 123 -124 -119 KV3 124 -125 -126 KV3 125 -126 KV3 126 KV3 127 -123 KV4 128 -129 KV4 129

  18. NASA's Radiation Belt Storm Probe Mission

    NASA Technical Reports Server (NTRS)

    Sibeck, David G.

    2011-01-01

    NASA's Radiation Belt Storm Probe (RBSP) mission, comprising two identically-instrumented spacecraft, is scheduled for launch in May 2012. In addition to identifying and quantifying the processes responsible for energizing, transporting, and removing energetic particles from the Earth's Van Allen radiation, the mission will determine the characteristics of the ring current and its effect upon the magnetosphere as a whole. The distances separating the two RBSP spacecraft will vary as they move along their 1000 km altitude x 5.8 RE geocentric orbits in order to enable the spacecraft to separate spatial from temporal effects, measure gradients that help identify particle sources, and determine the spatial extent of a wide array of phenomena. This talk explores the scientific objectives of the mission and the manner by which the mission has been tailored to achieve them.

  19. Van Allen Probe Explorations of Plasma Spatial and Temporal Scales in the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Niehof, J. T.; Larsen, B.; Skoug, R. M.; Reeves, G. D.; MacDonald, E.; Thomsen, M.; Funsten, H. O.; Friedel, R. H.

    2013-12-01

    We utilize the variable separation of the twin satellites of the Van Allen Probes mission to explore the time and spatial stability of plasma features in the inner magnetosphere. The spacecraft are in a leader-follower configuration with an approximately nine hour orbit, but with slightly different apogees and thus periods. Exploiting the resulting variation in separations, we survey differences in the plasma environment between inbound and outbound passes from a single satellite and between the two separated in time. The time separation ranges from minutes to 4.5 hours. From the HOPE instrument we obtain pitch angle resolved measurements of the plasma environment (for electrons, protons, helium, and oxygen). By utilizing both spacecraft, temporal and spatial effects are separated. By comparing temporal variations to drift and flow times, we determine which events' evolution is adequately described by simple flow or drift and which must result from more involved physics.

  20. Van Allen Probes Empirical Model of the Plasma Environment Inside Geostationary Orbit

    NASA Astrophysics Data System (ADS)

    Larsen, B.; Reeves, G. D.; Friedel, R. H. W.; Thomsen, M. F.; Skoug, R. M.; Funsten, H. O.; MacDonald, E.

    2014-12-01

    With the Van Allen probes nearing a full precession around the Earth we present a parameterized empirical model of the plasma properties in the inner magnetosphere. Data from the Los Alamos National Laboratory built Helium-Oxygen-Proton-Electron (HOPE) spectrometer on this this unparalleled two-satellite mission provides excellent coverage of the equatorial magnetosphere inside of geostationary, albeit over a limited range of geomagnetic activity. Fusing data and derived products from the two spacecraft a specification of the state of the inner magnetosphere has been created providing species resolved fluxes, partial densities, temperatures, anisotropies, and ratios. This full coverage model reproduces some well know phenomenology and presents some lesser know behaviors providing new insights into details of plasma dynamics inside geostationary orbit.

  1. On the metallic nature of carbon in allenes and heterocumulenes.

    PubMed

    Alcarazo, Manuel

    2011-03-07

    The IUPAC defines allenes as organic compounds having at least two double bonds from one carbon to two others. Thus the central carbon atom is in accord with the octet rule through the formation of two σ and two π bonds. However, this perspective highlights a series of recent experimental, as well as theoretical results, suggesting that depending on the substituents, this canonical description might not be the most adequate. In fact, in a growing number of examples the bond in allenes and related heterocumulenes is better described as an inner carbon that plays the role of the central atom of a "coordination complex" and interacts with its substituents as if they were ligands of this organic complex. This interpretation of the bond in allenes is especially useful in predicting the C(0), carbene or partial carbocationic character of the central carbon atom.

  2. Extreme enhancements and depletions of relativistic electrons in Earth's radiation belts

    NASA Astrophysics Data System (ADS)

    Turner, D. L.; Claudepierre, S. G.; O'Brien, T. P., III; Fennell, J. F.; Blake, J. B.; Baker, D. N.; Jaynes, A. N.; Morley, S.; Geoffrey, R.

    2015-12-01

    Earth's electron radiation belts consist of toroidal zones in near-Earth space characterized by intense levels of relativistic electrons with distinct energy-dependent boundaries. It has been known for decades that the outer electron radiation belt is highly variable, with electron intensities varying by orders of magnitude on timescales ranging from minutes to years. Now, we are gaining much insight into the nature of this extreme variability thanks to the unprecedented number of observatories capable of measuring radiation belt electrons, the most recent of which is NASA's Van Allen Probes mission. In this presentation, we analyze and review several of the most extreme events observed in Earth's outer radiation belt. We begin with very sudden and strong enhancements of the outer radiation belt that can result in several orders of magnitude enhancements of electron intensities up to several MeV that sometimes occur in less than one day. We compare and contrast two of the most extreme cases of sudden and strong enhancements from the Van Allen Probes era, 08-09 October 2012 and 17-18 March 2015, and review evidence of the dominant acceleration mechanism in each event. Sudden enhancements of the radiation belts can also occur from injections by interplanetary shocks impacting the magnetosphere, such as occurred on 24 March 1991. We compare shock characteristics from previous injection events to those from the Van Allen Probes era to investigate why none of the interplanetary shocks since September 2012 have caused MeV electron injections into the slot region and inner radiation belt, which has surprisingly been devoid of measurable quantities of >~1 MeV electrons throughout the Van Allen Probes era. Our last topic concerns loss processes. We discuss drastic loss events, known as "flux dropouts", and present evidence that these loss events can eliminate the vast majority of relativistic electrons in the outer radiation belt on time scales of only a few hours. We

  3. On the relation between radiation belt electrons and solar wind parameters/geomagnetic indices: Dependence on the first adiabatic invariant and L*

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Baker, D. N.; Jaynes, A. N.; Li, X.; Elkington, S. R.; Kanekal, S. G.; Spence, H. E.; Boyd, A. J.; Huang, C.-L.; Forsyth, C.

    2017-02-01

    The relation between radiation belt electrons and solar wind/magnetospheric processes is of particular interest due to both scientific and practical needs. Though many studies have focused on this topic, electron data from Van Allen Probes with wide L shell coverage and fine energy resolution, for the first time, enabled this statistical study on the relation between radiation belt electrons and solar wind parameters/geomagnetic indices as a function of first adiabatic invariant μ and L*. Good correlations between electron phase space density (PSD) and solar wind speed, southward IMF Bz, SYM-H, and AL indices are found over wide μ and L* ranges, with higher correlation coefficients and shorter time lags for low-μ electrons than high-μ electrons; the anticorrelation between electron PSD and solar wind proton density is limited to high-μ electrons at high L*. The solar wind dynamic pressure has dominantly positive correlation with low-μ electrons and negative correlation with high-μ electrons at different L*. In addition, electron PSD enhancements also correlate well with various solar wind/geomagnetic parameters, and for most parameters this correlation is even better than that of electron PSD while the time lag is also much shorter. Among all parameters investigated, AL index is shown to correlate the best with electron PSD enhancements, with correlation coefficients up to 0.8 for low-μ electrons (time lag 0 day) and 0.7 for high-μ electrons (time lag 1-2 days), suggesting the importance of seed and source populations provided by substorms in radiation belt electron PSD enhancements.

  4. Clarence Allen talks about the responsibilities in earthquake prediction

    USGS Publications Warehouse

    Spall, H.

    1978-01-01

    Dr. Clarence R. Allen is professor of geology and geophysics at the California Institute of Technology. He has been a member of advisory panels to the Executive Office of the President, National Academy of Sciences, National Science Foundation, U.S Geological Survey, UNESCO, California State Mining and Geology Board, and the California Department of Water Resources. Dr. Allen has been President of both the Geological Society of America and the Seismological Society of America (SSA). The title of this interview is based on his presidential address to the SSA in 1976. 

  5. 5. Historic American Buildings Survey Harold Allen, Photographer June 1964 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. Historic American Buildings Survey Harold Allen, Photographer June 1964 TRIPLE STAINED GLASS WINDOWS AND COLUMN SUPPORTING BALCONY (EAST WINDOWS IN SOUTH WALL OF MAIN FLOOR OF AUDITORIUM) - Kehilath Anshe Ma'ariv Synagogue, 3301 South Indiana Avenue, Chicago, Cook County, IL

  6. Van Allen Probes Science Gateway: A Centralized Data Access Point

    NASA Astrophysics Data System (ADS)

    Romeo, G.; Barnes, R. J.; Ukhorskiy, A. Y.; Sotirelis, T.; Stephens, G. K.; Kessel, R.; Potter, M.

    2015-12-01

    The Van Allen Probes Science Gateway acts a centralized interface to the instrument Science Operation Centers (SOCs), provides mission planning tools, and hosts a number of science related activities such as the mission bibliography. Most importantly, the Gateway acts as the primary site for processing and delivering the Van Allen Probes Space Weather data to users. Over the past years, the web-site has been completely redesigned with the focus on easier navigation and improvements of the existing tools such as the orbit plotter, position calculator and magnetic footprint tool. In addition, a new data plotting facility has been added. Based on HTML5, which allows users to interactively plot Van Allen Probes science and space weather data. The user can tailor the tool to display exactly the plot they wish to see and then share this with other users via either a URL or by QR code. Various types of plots can be created, including, simple time series, data plotted as a function of orbital location, and time versus L-Shell, capability of visualizing data from both probes (A & B) on the same plot. In cooperation with all Van Allen Probes Instrument SOCs, the Science Gateway will soon be able to serve higher level data products (Level 3), and to visualize them via the above mentioned HTML5 interface. Users will also be able to create customized CDF files on the fly.

  7. Near-earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations

    DOE PAGES

    Dai, Lei; Wang, Chi; Duan, Suping; ...

    2015-08-10

    Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeV electron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L~5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ~40 s and a dispersionless injection of electrons up to ~3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front.more » Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt (L > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.« less

  8. Near-earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations

    SciTech Connect

    Dai, Lei; Wang, Chi; Duan, Suping; He, Zhaohai; Wygant, John R.; Cattell, Cynthia A.; Tao, Xin; Su, Zhenpeng; Kletzing, Craig; Baker, Daniel N.; Li, Xinlin; Malaspina, David; Blake, J. Bernard; Fennell, Joseph; Claudepierre, Seth; Turner, Drew L.; Reeves, Geoffrey D.; Funsten, Herbert O.; Spence, Harlan E.; Angelopoulos, Vassilis; Fruehauff, Dennis; Chen, Lunjin; Thaller, Scott; Breneman, Aaron; Tang, Xiangwei

    2015-08-10

    Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeV electron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L~5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ~40 s and a dispersionless injection of electrons up to ~3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt (L > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.

  9. Near-Earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations.

    PubMed

    Dai, Lei; Wang, Chi; Duan, Suping; He, Zhaohai; Wygant, John R; Cattell, Cynthia A; Tao, Xin; Su, Zhenpeng; Kletzing, Craig; Baker, Daniel N; Li, Xinlin; Malaspina, David; Blake, J Bernard; Fennell, Joseph; Claudepierre, Seth; Turner, Drew L; Reeves, Geoffrey D; Funsten, Herbert O; Spence, Harlan E; Angelopoulos, Vassilis; Fruehauff, Dennis; Chen, Lunjin; Thaller, Scott; Breneman, Aaron; Tang, Xiangwei

    2015-08-16

    Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeVelectron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L ∼ 5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ∼40 s and a dispersionless injection of electrons up to ∼3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt (L > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.

  10. Nonlinear Whistler Wave Physics in the Radiation Belts

    NASA Astrophysics Data System (ADS)

    Crabtree, Chris

    2016-10-01

    Wave particle interactions between electrons and whistler waves are a dominant mechanism for controlling the dynamics of energetic electrons in the radiation belts. They are responsible for loss, via pitch-angle scattering of electrons into the loss cone, and energization to millions of electron volts. It has previously been theorized that large amplitude waves on the whistler branch may scatter their wave-vector nonlinearly via nonlinear Landau damping leading to important consequences for the global distribution of whistler wave energy density and hence the energetic electrons. It can dramatically reduce the lifetime of energetic electrons in the radiation belts by increasing the pitch angle scattering rate. The fundamental building block of this theory has now been confirmed through laboratory experiments. Here we report on in situ observations of wave electro-magnetic fields from the EMFISIS instrument on board NASA's Van Allen Probes that show the signatures of nonlinear scattering of whistler waves in the inner radiation belts. In the outer radiation belts, whistler mode chorus is believed to be responsible for the energization of electrons from 10s of Kev to MeV energies. Chorus is characterized by bursty large amplitude whistler mode waves with frequencies that change as a function of time on timescales corresponding to their growth. Theories explaining the chirping have been developed for decades based on electron trapping dynamics in a coherent wave. New high time resolution wave data from the Van Allen probes and advanced spectral techniques are revealing that the wave dynamics is highly structured, with sub-elements consisting of multiple chirping waves with discrete frequency hops between sub-elements. Laboratory experiments with energetic electron beams are currently reproducing the complex frequency vs time dynamics of whistler waves and in addition revealing signatures of wave-wave and beat-wave nonlinear wave-particle interactions. These new data

  11. Simulation of energy-dependent electron diffusion processes in the Earth's outer radiation belt

    NASA Astrophysics Data System (ADS)

    Ma, Q.; Li, W.; Thorne, R. M.; Nishimura, Y.; Zhang, X.-J.; Reeves, G. D.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Henderson, M. G.; Spence, H. E.; Baker, D. N.; Blake, J. B.; Fennell, J. F.; Angelopoulos, V.

    2016-05-01

    The radial and local diffusion processes induced by various plasma waves govern the highly energetic electron dynamics in the Earth's radiation belts, causing distinct characteristics in electron distributions at various energies. In this study, we present our simulation results of the energetic electron evolution during a geomagnetic storm using the University of California, Los Angeles 3-D diffusion code. Following the plasma sheet electron injections, the electrons at different energy bands detected by the Magnetic Electron Ion Spectrometer (MagEIS) and Relativistic Electron Proton Telescope (REPT) instruments on board the Van Allen Probes exhibit a rapid enhancement followed by a slow diffusive movement in differential energy fluxes, and the radial extent to which electrons can penetrate into depends on energy with closer penetration toward the Earth at lower energies than higher energies. We incorporate radial diffusion, local acceleration, and loss processes due to whistler mode wave observations to perform a 3-D diffusion simulation. Our simulation results demonstrate that chorus waves cause electron flux increase by more than 1 order of magnitude during the first 18 h, and the subsequent radial extents of the energetic electrons during the storm recovery phase are determined by the coupled radial diffusion and the pitch angle scattering by EMIC waves and plasmaspheric hiss. The radial diffusion caused by ULF waves and local plasma wave scattering are energy dependent, which lead to the observed electron flux variations with energy dependences. This study suggests that plasma wave distributions in the inner magnetosphere are crucial for the energy-dependent intrusions of several hundred keV to several MeV electrons.

  12. Comparison between Low and High Latitude Lightning VLF Wave Propagation Using WWLLN and Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Zheng, H.; Holzworth, R. H., II; Brundell, J. B.; Wygant, J. R.; Hospodarsky, G. B.; Mozer, F.; Jacobson, A. R.; Bonnell, J. W.

    2014-12-01

    Lightning produces strong broadband radio waves, called "sferics", which propagate in the Earth-ionosphere waveguide and are detected thousands of kilometers away from their source. Global real-time detection of lightning strokes including their time, location and energy, is conducted with the World Wide Lightning Location Network (WWLLN). In the ionosphere, these sferics couple into very low frequency (VLF) whistler waves which propagate obliquely to the Earth's magnetic field. Possible one-to-one coincidence between lightning and VLF whistler wave is already found by the conjunction work between WWLLN and Van Allen Probes (formerly known as the Radiation Belt Storm Probes (RBSP)). The previous global study showed a good match between WWLLN sferics and RBSP VLF whistlers at low L shell region (L < 3). In this summer, we started obtaining high sampling mode data from RBSP near the apogee. Initial results indicate many one-to-one coincidences at high L shell region (L>4). The whistlers observed at high L shell region are often nose whistlers. In our work, we will show the statistics results between WWLLN sferics and RBSP VLF whistlers at high L shell region. This talk will also explore the difference between low and high latitude lightning VLF wave propagation.

  13. Statistical Features of EMIC Waves Observed on Van Allen Probes in the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Lee, D. Y.; Roh, S. J.; Cho, J.; Shin, D. K.; Hwang, J.; Kim, K. C.; Kurth, W. S.; Kletzing, C.; Wygant, J. R.; Thaller, S. A.

    2015-12-01

    Electromagnetic ion cyclotron (EMIC) waves are one of the key plasma waves that can affect charged particle dynamics in the Earth's inner magnetosphere. Knowledge of global distribution of the EMIC waves is critical for accurately assessing the significance of its interaction with charged particles. With the Van Allen Probes EMFISIS observations, we have surveyed EMIC events for ~2.5 years period. We have identified well-defined, banded wave activities only, as distinguished from broad band wave activities. We have obtained global distribution of occurrence of the identified waves with distinction between H- and He-bands. We compare it with previous observations such as THEMIS and CRRES. For the identified events we have drawn all the basic wave properties including wave frequency, polarization, wave normal angle. In addition, we have distinguished the EMIC events that occur inside the plasmasphere and at the plasmapause from those outside the plasmasphere. Finally, we have tested solar wind and geomagnetic dependence of the wave events. We give discussions about implications of these observations on wave generation mechanism and interaction with radiation belt electrons.

  14. Study of lightning whistler waves observed at high L-shells on Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Zheng, H.; Holzworth, R.; Brundell, J. B.; Wygant, J. R.; Hospodarsky, G. B.; Mozer, F.; Jacobson, A. R.; Bonnell, J. W.

    2015-12-01

    Lightning produces strong broadband radio waves, called "sferics", which propagate in the Earth-ionosphere waveguide and are detected thousands of kilometers away from their source. Global real-time detection of lightning strokes including their time, location and energy, is conducted with the World Wide Lightning Location Network (WWLLN). In the ionosphere, these sferics couple into very low frequency (VLF) whistler waves which propagate obliquely to the Earth's magnetic field. In our previous work, one-to-one coincidence between lightning and whistler waves is already found by the conjunction work between WWLLN and Van Allen Probes (formerly known as the Radiation Belt Storm Probes (RBSP)). The previous global study showed a good match between WWLLN sferics and RBSP lightning whistlers at low L-shell region (L < 3). More case studies indicated that this kind of one-to-one coincidence can be extended to a high L-shell region. Since September 2012 to now (July 2015), EMFISIS instrument has already recorded 3-D waveform data with 35 ksamples/s for 527,279 and 542,346 of 6-second snapshots, respectively for RBSP-A and RBSP-B. 461,572 and 478,510 of snapshots with L-shell value larger than 3 are used in our work. In our work, we will show the distribution of lightning whistler waves at high L-shells. This talk will also explore the upper cutoff frequency of lightning whistler waves at high L-shells.

  15. Isomer-specific combustion chemistry in allene and propyne flames

    SciTech Connect

    Hansen, Nils; Miller, James A.; Westmoreland, Phillip R.; Kasper, Tina; Kohse-Hoeinghaus, Katharina; Wang, Juan; Cool, Terrill A.

    2009-11-15

    A combined experimental and modeling study is performed to clarify the isomer-specific combustion chemistry in flames fueled by the C{sub 3}H{sub 4} isomers allene and propyne. To this end, mole fraction profiles of several flame species in stoichiometric allene (propyne)/O{sub 2}/Ar flames are analyzed by means of a chemical kinetic model. The premixed flames are stabilized on a flat-flame burner under a reduced pressure of 25 Torr (=33.3 mbar). Quantitative species profiles are determined by flame-sampling molecular-beam mass spectrometry, and the isomer-specific flame compositions are unraveled by employing photoionization with tunable vacuum-ultraviolet synchrotron radiation. The temperature profiles are measured by OH laser-induced fluorescence. Experimental and modeled mole fraction profiles of selected flame species are discussed with respect to the isomer-specific combustion chemistry in both flames. The emphasis is put on main reaction pathways of fuel consumption, of allene and propyne isomerization, and of isomer-specific formation of C{sub 6} aromatic species. The present model includes the latest theoretical rate coefficients for reactions on a C{sub 3}H{sub 5} potential [J.A. Miller, J.P. Senosiain, S.J. Klippenstein, Y. Georgievskii, J. Phys. Chem. A 112 (2008) 9429-9438] and for the propargyl recombination reactions [Y. Georgievskii, S.J. Klippenstein, J.A. Miller, Phys. Chem. Chem. Phys. 9 (2007) 4259-4268]. Larger peak mole fractions of propargyl, allyl, and benzene are observed in the allene flame than in the propyne flame. In these flames virtually all of the benzene is formed by the propargyl recombination reaction. (author)

  16. To Belt or Not To Belt?

    ERIC Educational Resources Information Center

    Vail, Kathleen

    1999-01-01

    The National Highway Traffic Transportation Safety Administration (NHTSA) is in the midst of the first school-bus crash tests in more than 10 years. Its report is expected in June 2000, and those on both sides of the seat-belt debate are waiting to see what NHTSA will recommend on passenger restraints in large school buses. A sidebar lists sources…

  17. Van Allen Probes Science Gateway and Space Weather Data Processing

    NASA Astrophysics Data System (ADS)

    Romeo, G.; Barnes, R. J.; Weiss, M.; Fox, N. J.; Mauk, B.; Potter, M.; Kessel, R.

    2014-12-01

    The Van Allen Probes Science Gateway acts as a centralized interface to the instrument Science Operation Centers (SOCs), provides mission planning tools, and hosts a number of science related activities such as the mission bibliography. Most importantly, the Gateway acts as the primary site for processing and delivering the VAP Space Weather data to users. Over the past year, the web-site has been completely redesigned with the focus on easier navigation and improvements of the existing tools such as the orbit plotter, position calculator and magnetic footprint tool. In addition, a new data plotting facility has been added. Based on HTML5, which allows users to interactively plot Van Allen Probes summary and space weather data. The user can tailor the tool to display exactly the plot they wish to see and then share this with other users via either a URL or by QR code. Various types of plots can be created, including simple time series, data plotted as a function of orbital location, and time versus L-Shell. We discuss the new Van Allen Probes Science Gateway and the Space Weather Data Pipeline.

  18. Observations of purely compressional waves in the upper ULF band observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Posch, J. L.; Engebretson, M. J.; Johnson, J.; Kim, E. H.; Thaller, S. A.; Wygant, J. R.; Kletzing, C.; Smith, C. W.; Reeves, G. D.

    2014-12-01

    Purely compressional electromagnetic waves, also denoted fast magnetosonic waves, equatorial noise, and ion Bernstein modes, can both heat thermal protons and accelerate electrons up to relativistic energies. These waves have been observed both in the near-equatorial region in the inner magnetosphere and in the plasma sheet boundary layer. Although these waves have been observed by various types of satellite instruments (DC and AC magnetometers and electric field sensors), most recent studies have used data from AC sensors, and many have been restricted to frequencies above ~50 Hz. We report here on a survey of ~200 of these waves, based on DC electric and magnetic field data from the EFW double probe and EMFISIS fluxgate magnetometer instruments, respectively, on the Van Allen Probes spacecraft during its first two years of operation. The high sampling rate of these instruments makes it possible to extend observational studies of the lower frequency population of such waves to lower L shells than any previous study. These waves, often with multiple harmonics of the local proton gyrofrequency, were observed both inside and outside the plasmapause, in regions with plasma number densities ranging from 10 to >1000 cm-3. Wave occurrence was sharply peaked near the magnetic equator and occurred at L shells from below 2 to ~6 (the spacecraft apogee). Waves appeared at all local times but were more common from noon to dusk. Outside the plasmapause, occurrence maximized broadly across noon. Inside the plasmapause, occurrence maximized in the dusk sector, in an extended plasmasphere. Every event occurred in association with a positive gradient in the HOPE omnidirectional proton flux in the range between 2 keV and 10 keV. The Poynting vector, determined for 8 events, was in all cases directed transverse to B, but with variable azimuth, consistent with earlier models and observations.

  19. Wave Distribution Functions of Plasmaspheric Hiss and their Effects on Radiation Belt Dynamics

    NASA Astrophysics Data System (ADS)

    Santolik, O.; Ripoll, J. F.; Kurth, W. S.; Hospodarsky, G. B.; Kletzing, C.

    2015-12-01

    Plasmaspheric hiss is formed by whistler-mode waves which play an important role in the dynamics the Earth's radiation belts, specifically in connection with the slot region between the inner and outer Van Allen belts. The origin of plasmaspheric hiss is still a subject of discussions and these waves are known for their complex propagation properties. They are often far from a single plane wave approximation, forming a continuous distribution of the wave energy density with respect to the wave vector direction (wave distribution function). Analysis of polarization and propagation parameters of these waves provides us with inputs for modeling of radiation belt dynamics. We use the data of the Waves instrument of Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) onboard the Van Allen Probes spacecraft, to analyze simultaneous measurements of all electric and magnetic field components, together with measurements of the plasma density based on the determination of the upper hybrid resonance frequency. Using this unique data set we estimate the wave distribution functions of plasmaspheric hiss and we model the effects of these waves on the decay rates of radiation belt electrons through quasilinear pitch angle diffusion.

  20. Ionic composition of the earth's radiation belts

    NASA Technical Reports Server (NTRS)

    Spjeldvik, W. N.

    1983-01-01

    Several different ion species have been positively identified in the earth's radiation belts. Besides protons, there are substantial fluxes of helium, carbon and oxygen ions, and there are measurable quantities of even heavier ions. European, American and Soviet space experimenters have reported ion composition measurements over wide ranges of energies: at tens of keV (ring-current energies) and below, and at hundreds of keV and above. There is still a gap in the energy coverage from several tens to several hundreds of keV where little observational data are available. In this review emphasis is placed on the radiation belt ionic structure above 100 keV. Both quiet time conditions and geomagnetic storm periods are considered, and comparison of the available space observations is made with theoretical analysis of geomagnetically trapped ion spatial, energy and charge state distributions.

  1. Kalman Filtering and Smoothing of the Van Allen Probes Observations to Estimate the Radial, Energy and Pitch Angle Diffusion Rates

    NASA Astrophysics Data System (ADS)

    Podladchikova, T.; Shprits, Y.; Kellerman, A. C.

    2015-12-01

    The Kalman filter technique combines the strengths of new physical models of the Earth's radiation belts with long-term spacecraft observations of electron fluxes and therefore provide an extremely useful method for the analysis of the state and evolution of the electron radiation belts. However, to get the reliable data assimilation output, the Kalman filter application is confronted with a set of fundamental problems. E.g., satellite measurements are usually limited to a single location in space, which confines the reconstruction of the global evolution of the radiation environment. The uncertainties arise from the imperfect description of the process dynamics and the presence of observation errors, which may cause the failure of data assimilation solution. The development of adaptive Kalman filter that combines the Van Allen Probes data and 3-D VERB code, its accurate customizations in the reconstruction of model describing the phase space density (PSD) evolution, extension of the possibilities to use measurement information, and the model adjustment by developing the identification techniques of model and measurement errors allowed us to reveal hidden and implicit regularities of the PSD dynamics and obtain quantitative and qualitative estimates of radial, energy and pitch angle diffusion characteristics from satellite observations. In this study we propose an approach to estimate radial, energy and pitch angle diffusion rates, as well as the direction of their propagation.

  2. Van Allen Probes observations of unusually low frequency whistler mode waves observed in association with moderate magnetic storms: Statistical study

    PubMed Central

    Breneman, A. W.; Thaller, S. A.; Wygant, J. R.; Kletzing, C. A.; Kurth, W. S.

    2015-01-01

    Abstract We show the first evidence for locally excited chorus at frequencies below 0.1 f ce (electron cyclotron frequency) in the outer radiation belt. A statistical study of chorus during geomagnetic storms observed by the Van Allen Probes found that frequencies are often dramatically lower than expected. The frequency at peak power suddenly stops tracking the equatorial 0.5 f ce and f/f ce decreases rapidly, often to frequencies well below 0.1 f ce (in situ and mapped to equator). These very low frequency waves are observed both when the satellites are close to the equatorial plane and at higher magnetic latitudes. Poynting flux is consistent with generation at the equator. Wave amplitudes can be up to 20 to 40 mV/m and 2 to 4 nT. We conclude that conditions during moderate to large storms can excite unusually low frequency chorus, which is resonant with more energetic electrons than typical chorus, with critical implications for understanding radiation belt evolution. PMID:27667871

  3. Belt conveyor apparatus

    DOEpatents

    Oakley, David J.; Bogart, Rex L.

    1987-01-01

    A belt conveyor apparatus according to this invention defines a conveyance path including a first pulley and at least a second pulley. An endless belt member is adapted for continuous travel about the pulleys and comprises a lower portion which engages the pulleys and an integral upper portion adapted to receive objects therein at a first location on said conveyance path and transport the objects to a second location for discharge. The upper belt portion includes an opposed pair of longitudinally disposed crest-like members, biased towards each other in a substantially abutting relationship. The crest-like members define therebetween a continuous, normally biased closed, channel along the upper belt portion. Means are disposed at the first and second locations and operatively associated with the belt member for urging the normally biased together crest-like members apart in order to provide access to the continuous channel whereby objects can be received into, or discharged from the channel. Motors are in communication with the conveyance path for effecting the travel of the endless belt member about the conveyance path. The conveyance path can be configured to include travel through two or more elevations and one or more directional changes in order to convey objects above, below and/or around existing structures.

  4. Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013

    DOE PAGES

    Su, Zhenpeng; Gao, Zhonglei; Reeves, Geoffrey D.; ...

    2016-07-01

    Radiation belt electron flux dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt electron fluxes exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances (L > 4.5), energies (~500 keV to several MeV) and equatorial pitch angles (0° ≤ αe ≤ 180°). STEERB simulations show that the relativistic electron loss in the region L = 4.5–6.0 was primarily caused bymore » the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Furthermore, our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.« less

  5. Solar wind conditions leading to efficient radiation belt electron acceleration: A superposed epoch analysis

    SciTech Connect

    Li, W.; Thorne, R. M.; Bortnik, J.; Baker, D. N.; Reeves, G. D.; Kanekal, S. G.; Spence, H. E.; Green, J. C.

    2015-09-07

    In this study by determining preferential solar wind conditions leading to efficient radiation belt electron acceleration is crucial for predicting radiation belt electron dynamics. Using Van Allen Probes electron observations (>1 MeV) from 2012 to 2015, we identify a number of efficient and inefficient acceleration events separately to perform a superposed epoch analysis of the corresponding solar wind parameters and geomagnetic indices. By directly comparing efficient and inefficient acceleration events, we clearly show that prolonged southward Bz, high solar wind speed, and low dynamic pressure are critical for electron acceleration to >1 MeV energies in the heart of the outer radiation belt. We also evaluate chorus wave evolution using the superposed epoch analysis for the identified efficient and inefficient acceleration events and find that chorus wave intensity is much stronger and lasts longer during efficient electron acceleration events, supporting the scenario that chorus waves play a key role in MeV electron acceleration.

  6. Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013

    SciTech Connect

    Su, Zhenpeng; Gao, Zhonglei; Reeves, Geoffrey D.; Funsten, Herbert O.; Zhu, Hui; Li, Wen; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H. E.; Baker, D. N.; Blake, J. B.; Wygant, J. R.

    2016-07-01

    Radiation belt electron flux dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt electron fluxes exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances (L > 4.5), energies (~500 keV to several MeV) and equatorial pitch angles (0° ≤ αe ≤ 180°). STEERB simulations show that the relativistic electron loss in the region L = 4.5–6.0 was primarily caused by the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Furthermore, our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.

  7. Study the Precipitation of Radiation Belt Electrons during the Rapid Dropout Events

    NASA Astrophysics Data System (ADS)

    Tu, W.; Cunningham, G.; Li, X.; Chen, Y.

    2015-12-01

    During the main phase of storms, the relativistic electron flux in the radiation belt can drop by orders of magnitude on timescales of a few hours. Where do the electrons go? This is one of the most important outstanding questions in radiation belt studies. Radiation belt electrons can be lost either by transport across the magnetopause into interplanetary space or by precipitation into the atmosphere. In this work we first conduct a survey of the MeV electron dropouts using the Van Allen Probes data in conjunction with the low-altitude measurements of precipitating electrons by 6 NOAA/POES satellites. The dropout events are categorized into three types: precipitation-loss dominant, outward radial diffusion dominant, or with contributions from both mechanisms. The survey results suggest the relative importance of precipitation and outward radial diffusion to the fast dropouts of radiation belt electrons, and their extent in L-shell and electron energy. Then, for specific events identified as dominated by precipitation loss, we use the Drift-Diffusion model, which includes the effects of azimuthal drift and pitch angle diffusion, to simulate both the electron dropout observed by Van Allen Probes and the distributions of drift-loss-cone electrons observed by multiple low-earth-orbit satellites (6 POES and the Colorado Student Space Weather Experiment). The model quantifies the electron precipitation loss and pitch angle diffusion coefficient, Dxx, with high temporal and spatial resolution. Finally, by comparing the Dxx derived from the model with those estimated from the quasi-linear theory using wave data from Van Allen Probes and other event-specific wave models, we are able to test the validity of quasi-linear theory and seek direct evidence of the wave-particle interactions during the dropouts.

  8. Ring current pressure estimation with RAM-SCB using data assimilation and Van Allen Probe flux data

    NASA Astrophysics Data System (ADS)

    Godinez, H. C.; Yu, Y.; Lawrence, E.; Henderson, M. G.; Larsen, B.; Jordanova, V. K.

    2016-12-01

    Capturing and subsequently modeling the influence of tail plasma injections on the inner magnetosphere is important for understanding the formation and evolution of the ring current. In this study, the ring current distribution is estimated with the Ring Current-Atmosphere Interactions Model with Self-Consistent Magnetic field (RAM-SCB) using, for the first time, data assimilation techniques and particle flux data from the Van Allen Probes. The state of the ring current within the RAM-SCB model is corrected via an ensemble based data assimilation technique by using proton flux from one of the Van Allen Probes, to capture the enhancement of the ring current following an isolated substorm event on 18 July 2013. The results show significant improvement in the estimation of the ring current particle distributions in the RAM-SCB model, leading to better agreement with observations. This newly implemented data assimilation technique in the global modeling of the ring current thus provides a promising tool to improve the characterization of particle distribution in the near-Earth regions.

  9. Ring Current Pressure Estimation withRAM-SCB using Data Assimilation and VanAllen Probe Flux Data

    NASA Astrophysics Data System (ADS)

    Godinez, H. C.; Yu, Y.; Henderson, M. G.; Larsen, B.; Jordanova, V.

    2015-12-01

    Capturing and subsequently modeling the influence of tail plasma injections on the inner magnetosphere is particularly important for understanding the formation and evolution of Earth's ring current. In this study, the ring current distribution is estimated with the Ring Current-Atmosphere Interactions Model with Self-Consistent Magnetic field (RAM-SCB) using, for the first time, data assimilation techniques and particle flux data from the Van Allen Probes. The state of the ring current within the RAM-SCB is corrected via an ensemble based data assimilation technique by using proton flux from one of the Van Allen Probes, to capture the enhancement of ring current following an isolated substorm event on July 18 2013. The results show significant improvement in the estimation of the ring current particle distributions in the RAM-SCB model, leading to better agreement with observations. This newly implemented data assimilation technique in the global modeling of the ring current thus provides a promising tool to better characterize the effect of substorm injections in the near-Earth regions. The work is part of the Space Hazards Induced near Earth by Large, Dynamic Storms (SHIELDS) project in Los Alamos National Laboratory.

  10. Source and seed populations for relativistic electrons: Their roles in radiation belt changes

    DOE PAGES

    Jaynes, A. N.; Baker, D. N.; Singer, H. J.; ...

    2015-09-09

    Strong enhancements of outer Van Allen belt electrons have been shown to have a clear dependence on solar wind speed and on the duration of southward interplanetary magnetic field. However, individual case study analyses also have demonstrated that many geomagnetic storms produce little in the way of outer belt enhancements and, in fact, may produce substantial losses of relativistic electrons. In this study, focused upon a key period in August–September 2014, we use GOES geostationary orbit electron flux data and Van Allen Probes particle and fields data to study the process of radiation belt electron acceleration. One particular interval, 13–22more » September, initiated by a short-lived geomagnetic storm and characterized by a long period of primarily northward interplanetary magnetic field (IMF), showed strong depletion of relativistic electrons (including an unprecedented observation of long-lasting depletion at geostationary orbit) while an immediately preceding, and another immediately subsequent, storm showed strong radiation belt enhancement. We demonstrate with these data that two distinct electron populations resulting from magnetospheric substorm activity are crucial elements in the ultimate acceleration of highly relativistic electrons in the outer belt: the source population (tens of keV) that give rise to VLF wave growth and the seed population (hundreds of keV) that are, in turn, accelerated through VLF wave interactions to much higher energies. ULF waves may also play a role by either inhibiting or enhancing this process through radial diffusion effects. Furthermore, if any components of the inner magnetospheric accelerator happen to be absent, the relativistic radiation belt enhancement fails to materialize.« less

  11. Source and seed populations for relativistic electrons: Their roles in radiation belt changes

    SciTech Connect

    Jaynes, A. N.; Baker, D. N.; Singer, H. J.; Rodriguez, J. V.; Loto'aniu, T. M.; Ali, A. F.; Elkington, S. R.; Li, X.; Kanekal, S. G.; Claudepierre, S. G.; Fennell, J. F.; Li, W.; Thorne, R. M.; Kletzing, C. A.; Spence, H. E.; Reeves, G. D.

    2015-09-09

    Strong enhancements of outer Van Allen belt electrons have been shown to have a clear dependence on solar wind speed and on the duration of southward interplanetary magnetic field. However, individual case study analyses also have demonstrated that many geomagnetic storms produce little in the way of outer belt enhancements and, in fact, may produce substantial losses of relativistic electrons. In this study, focused upon a key period in August–September 2014, we use GOES geostationary orbit electron flux data and Van Allen Probes particle and fields data to study the process of radiation belt electron acceleration. One particular interval, 13–22 September, initiated by a short-lived geomagnetic storm and characterized by a long period of primarily northward interplanetary magnetic field (IMF), showed strong depletion of relativistic electrons (including an unprecedented observation of long-lasting depletion at geostationary orbit) while an immediately preceding, and another immediately subsequent, storm showed strong radiation belt enhancement. We demonstrate with these data that two distinct electron populations resulting from magnetospheric substorm activity are crucial elements in the ultimate acceleration of highly relativistic electrons in the outer belt: the source population (tens of keV) that give rise to VLF wave growth and the seed population (hundreds of keV) that are, in turn, accelerated through VLF wave interactions to much higher energies. ULF waves may also play a role by either inhibiting or enhancing this process through radial diffusion effects. Furthermore, if any components of the inner magnetospheric accelerator happen to be absent, the relativistic radiation belt enhancement fails to materialize.

  12. Solar Neutrons and the Earth's Radiation Belts.

    PubMed

    Lingenfelter, R E; Flamm, E J

    1964-04-17

    The intensity and spectrum of solar neutrons in the vicinity of the earth are calculated on the assumption that the low-energy protons recently detected in balloon and satellite flights are products of solar neutron decay. The solar-neutron flux thus obtained exceeds the global average cosmic-ray neutron leakage above 10 Mev, indicating that it may be an important source of both the inner and outer radiation belts. Neutron measurements in the atmosphere are reviewed and several features of the data are found to be consistent with the estimated solar neutron spectrum.

  13. Modeling Loss and Rebuilding of the Earth's Outer Zone Electrons and Comparison with Van Allen Probes Measurements

    NASA Astrophysics Data System (ADS)

    Hudson, M. K.; Kress, B. T.; Li, Z.; Paral, J.; Wiltberger, M. J.

    2014-12-01

    Quantifying the competition between radiation belt electron energization due to radial transport and loss to the magnetopause and to the atmosphere is critical to understanding the dynamic changes in outer zone radiation belt electron flux response to solar wind drivers. Plasmasheet electron injection, both due to enhanced convection and substorm dipolarization, provides a source population for generation of whistler mode chorus and seed population for local acceleration. We now have available ~22 months of unprecedented measurements in energy and pitch angle resolution of electrons spanning the energy range from injected plasmasheet to multi-MeV electrons from the twin Van Allen Probes spacecraft in near-equatorial plane elliptical orbits, with apogee at 5.8 Re; and two Balloon Array for Relativistic Radiation Belt Electron Losses (BARREL) campaigns during January-February 2013 and 2014, each establishing a longitudinal array of precipitation measurements extending to relativistic energies via measured Bremsstrahlung x-rays. In addition to this arsenal of data, a set of modeling tools has been developed to examine dynamics of electrons in the magnetosphere. These tools calculate electron trajectories in time-dependent magnetohydrodyanmic (MHD) fields using the Lyon-Fedder-Mobarry global MHD model coupled with the Rice Convection Model to determine the E and B field response to solar wind drivers. With these tools we can follow electron dynamics including response to Ultra Low Frequency (ULF) waves which cause radial transport and energization for inward radial gradient as well as enhanced loss to the magnetopause for outward gradient. These tools have been applied to date to the large equinoctial storms of fall 2012, spring and fall 2013, in addition to moderate storms during BARREL balloon campaigns in both winters 2013 and 2014. Isolated substorm response can clearly be identified for the latter, while plasmasheet injection of electrons during periods of strong

  14. Detecting Mass Loss in Main Belt Asteroids

    NASA Astrophysics Data System (ADS)

    Sandberg, Erik; Rajagopal, Jayadev; Ridgway, Susan E.; Kotulla, Ralf C.; Valdes, Francisco; Allen, Lori

    2016-01-01

    Sandberg, E., Rajagopal, J., Ridgway, S.E, Kotulla, R., Valdes, F., Allen, L.The Dark Energy Camera (DECam) on the 4m Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO) is being used for a survey of Near Earth Objects (NEOs). Here we attempt to identify mass loss in main belt asteroids (MBAs) from these data. A primary motivation is to understand the role that asteroids may play in supplying dust and gas for debris disks. This work focuses on finding methods to automatically pick out asteroids that have qualities indicating possible mass loss. Two methods were chosen: looking for flux above a certain threshold in the asteroid's radial profile, and comparing its PSF to that of a point source. After sifting through 490 asteroids, several have passed these tests and should be followed up with a more rigorous analysis.Sandberg was supported by the NOAO/KPNO Research Experience for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program (AST-1262829)

  15. Neuroinformatics of the Allen Mouse Brain Connectivity Atlas.

    PubMed

    Kuan, Leonard; Li, Yang; Lau, Chris; Feng, David; Bernard, Amy; Sunkin, Susan M; Zeng, Hongkui; Dang, Chinh; Hawrylycz, Michael; Ng, Lydia

    2015-02-01

    The Allen Mouse Brain Connectivity Atlas is a mesoscale whole brain axonal projection atlas of the C57Bl/6J mouse brain. Anatomical trajectories throughout the brain were mapped into a common 3D space using a standardized platform to generate a comprehensive and quantitative database of inter-areal and cell-type-specific projections. This connectivity atlas has several desirable features, including brain-wide coverage, validated and versatile experimental techniques, a single standardized data format, a quantifiable and integrated neuroinformatics resource, and an open-access public online database (http://connectivity.brain-map.org/). Meaningful informatics data quantification and comparison is key to effective use and interpretation of connectome data. This relies on successful definition of a high fidelity atlas template and framework, mapping precision of raw data sets into the 3D reference framework, accurate signal detection and quantitative connection strength algorithms, and effective presentation in an integrated online application. Here we describe key informatics pipeline steps in the creation of the Allen Mouse Brain Connectivity Atlas and include basic application use cases.

  16. Galactic Plane SETI Observations with the Allen Telescope Array

    NASA Astrophysics Data System (ADS)

    Backus, P. R.; Tarter, J. C.; Davis, M. M.; Jordan, J. C.; Kilsdonk, T. N.; Shostak, G. S.; Ackerman, R.; DeBoer, D. R.; Dreher, J. W.; Harp, G. R.; Ross, J. E.; Stauduhar, R.

    2005-12-01

    In the spring of 2006, the Allen Telescope Array (ATA), a joint effort of the U.C. Berkeley Radio Astronomy Lab and the SETI Institute, will begin initial operations. Starting with 42 antennas out of a planned 350, the array will be equivalent to a single 40 meter dish. Using three phased beams, we will survey twenty square degrees around the galactic center for narrowband signals in the frequency range from 1410 to 1730 MHz (the "Water Hole"). Comparison of results from the beams will be used to eliminate signals from terrestrial and satellite sources. At these frequencies, the wide field of view of the array allows us to cover the 2 x 10 degree strip with five antenna positions. The field of view will track one of the five positions for up to five hours, while the phased beams are pointed within the field of view for 98 seconds per 20 MHz frequency band. During these SETI observations spanning approximately seven months, other radio astronomy observations of this very interesting region will run in parallel using two other independently tunable IF systems with a correlator and other phase array beams feeding other backend processors. Construction of the ATA is supported by private funding, primarily from the Paul G. Allen Foundation. The correlator for the ATA is supported by NSF Grant AST-0322309 to the UCB Radio Astronomy Lab.

  17. The Relative Deep Penetrations of Energetic Electrons and Ions into the Slot Region and Inner Belt

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Claudepierre, S. G.; Fennell, J. F.; Blake, J. B.; Larsen, B.; Skoug, R. M.; Funsten, H. O.; Baker, D. N.; Reeves, G. D.; Spence, H. E.

    2015-12-01

    Energetic electrons in the inner magnetosphere are distributed into two regions: the inner radiation belt and the outer radiation belt, with the slot region in between separating the two belts. Though many studies have focused on the outer belt dynamics, the energetic electrons in the slot region and especially inner belt did not receive much attention until recently. A number of new features regarding electrons in the low L region have been reported lately, including the abundance of 10s-100s of keV electrons in the inner belt, the frequent deep injections of 100s of keV electrons, and 90°-minimum pitch angle distributions of 100s of keV electrons in the inner belt and slot region. In this presentation, we focus on the relative deep injections into the slot region and inner belt of energetic electrons and ions using observations from HOPE and MagEIS instruments on the Van Allen Probes. It is shown that while 10s - 100s of keV electrons penetrate commonly deep into the low L region and are persistent in the inner belt, the deep injections of ions with similar energies occur rarely, possibly due to the fast loss of ions in the low L region. The energy spectra and pitch angle distributions of electrons and ions during injections are also very different, indicating the existence of different physical mechanisms acting on them. In addition, some intriguing similarities between lower energy ions and higher energy electrons will also be discussed.

  18. Evolution of chorus emissions into plasmaspheric hiss observed by Van Allen Probes

    DOE PAGES

    Zhou, Qinghua; Xiao, Fuliang; Yang, Chang; ...

    2016-05-09

    The two classes of whistler mode waves (chorus and hiss) play different roles in the dynamics of radiation belt energetic electrons. Chorus can efficiently accelerate energetic electrons, and hiss is responsible for the loss of energetic electrons. Previous studies have proposed that chorus is the source of plasmaspheric hiss, but this still requires an observational confirmation because the previously observed chorus and hiss emissions were not in the same frequency range in the same time. In this paper, we report simultaneous observations form Van Allen Probes that chorus and hiss emissions occurred in the same range ~300–1500 Hz with themore » peak wave power density about 10-5 nT2/Hz during a weak storm on 3 July 2014. Chorus emissions propagate in a broad region outside the plasmapause. Meanwhile, hiss emissions are confined inside the plasmasphere, with a higher intensity and a broader area at a lower frequency. A sum of bi-Maxwellian distribution is used to model the observed anisotropic electron distributions and to evaluate the instability of waves. A three-dimensional ray tracing simulation shows that a portion of chorus emission outside the plasmasphere can propagate into the plasmasphere and evolve into plasmaspheric hiss. Moreover, hiss waves below 1 kHz are more intense and propagate over a broader area than those above 1 kHz, consistent with the observation. Finally, the current results can explain distributions of the observed hiss emission and provide a further support for the mechanism of evolution of chorus into hiss emissions.« less

  19. Evolution of chorus emissions into plasmaspheric hiss observed by Van Allen Probes

    SciTech Connect

    Zhou, Qinghua; Xiao, Fuliang; Yang, Chang; Liu, Si; He, Yihua; Wygant, J. R.; Baker, D. N.; Spence, H. E.; Reeves, Geoffrey D.; Funsten, Herbert O.

    2016-05-09

    The two classes of whistler mode waves (chorus and hiss) play different roles in the dynamics of radiation belt energetic electrons. Chorus can efficiently accelerate energetic electrons, and hiss is responsible for the loss of energetic electrons. Previous studies have proposed that chorus is the source of plasmaspheric hiss, but this still requires an observational confirmation because the previously observed chorus and hiss emissions were not in the same frequency range in the same time. In this paper, we report simultaneous observations form Van Allen Probes that chorus and hiss emissions occurred in the same range ~300–1500 Hz with the peak wave power density about 10-5 nT2/Hz during a weak storm on 3 July 2014. Chorus emissions propagate in a broad region outside the plasmapause. Meanwhile, hiss emissions are confined inside the plasmasphere, with a higher intensity and a broader area at a lower frequency. A sum of bi-Maxwellian distribution is used to model the observed anisotropic electron distributions and to evaluate the instability of waves. A three-dimensional ray tracing simulation shows that a portion of chorus emission outside the plasmasphere can propagate into the plasmasphere and evolve into plasmaspheric hiss. Moreover, hiss waves below 1 kHz are more intense and propagate over a broader area than those above 1 kHz, consistent with the observation. Finally, the current results can explain distributions of the observed hiss emission and provide a further support for the mechanism of evolution of chorus into hiss emissions.

  20. Space Geoengineering: James A. Van Allen's Role in Detecting and Disrupting the Magnetosphere, 1958-1962 (Invited)

    NASA Astrophysics Data System (ADS)

    Fleming, J. R.

    2010-12-01

    James A. Van Allen’s celebrated discovery of Earth’s radiation belts in 1958 using Explorer 1 and 3 satellites was immediately followed by his agreement to monitor tests of nuclear weapons in space aimed at disrupting the magnetosphere. This is “space geoengineering” on a planetary scale. “Space is radioactive,” noted Van Allen’s colleague Eric Ray, and the military wanted to make it even more radioactive by nuclear detonations that, in time of war might disrupt enemy radio communications from half a world away and damage or destroy enemy intercontinental ballistic missiles. This study of Van Allen’s participation in Project Argus (1958) and Project Starfish (1962) is based on new posthumous accessions to the Van Allen Papers. At the time radio astronomers protested that, “No government has the right to change the environment in any significant way without prior international study and agreement.” Van Allen later regretted his participation in experiments that disrupted the natural magnetosphere. In a larger policy framework, the history of these space interventions and the protests they generated serve as a cautionary tale for today’s geoengineers who are proposing heavy-handed manipulation of the planetary environment as a response to future climate warming. Anyone claiming that geoengineering has not yet been attempted should be reminded of the planetary-scale engineering of these nukes in space. N. Christofilos describing the intended effect of the Argus nuclear explosions on the magnetosphere, which would direct a stream of radioactive particles along magnetic lines of force half a world away.

  1. Proton Therapy

    MedlinePlus

    ... for e-updates Please leave this field empty Proton Therapy SHARE Home > Treatment and Care > Treatments Listen ... a nucleus, which holds two types of particles—protons and neutrons. The nucleus is surrounded by electrons. ...

  2. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied while belts are...

  3. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied while belts are...

  4. Enantioselective Protonation

    PubMed Central

    Mohr, Justin T.; Hong, Allen Y.; Stoltz, Brian M.

    2010-01-01

    Enantioselective protonation is a common process in biosynthetic sequences. The decarboxylase and esterase enzymes that effect this valuable transformation are able to control both the steric environment around the proton acceptor (typically an enolate) and the proton donor (typically a thiol). Recently, several chemical methods to achieve enantioselective protonation have been developed by exploiting various means of enantiocontrol in different mechanisms. These laboratory transformations have proven useful for the preparation of a number of valuable organic compounds. PMID:20428461

  5. Moving Belt Radiator technology issues

    NASA Technical Reports Server (NTRS)

    White, K. Alan, III

    1988-01-01

    Development of the Moving Belt Radiator (MBR) as an advanced space radiator concept is discussed. The relative merits of Solid Belt (SBR) Liquid Belt (LBR), and Hybrid Belt (HBR) Radiators are described. Analytical and experimental efforts related to the dynamics of a rotating belt in microgravity are reviewed. The development of methods for transferring heat to the moving belt is discussed, and the results from several experimental investigations are summarized. Limited efforts related to the belt deployment and stowage, and to fabrication of a hybrid belt, are also discussed. Life limiting factors such as seal wear and micrometeroid resistance are identified. The results from various MBR point design studies for several power levels are compared with advanced Heat Pipe Radiator technology. MBR designs are shown to compare favorable at both 300 and 1000 K temperature levels. However, additional effort will be required to resolve critical technology issues and to demonstrate the advantage of MBR systems.

  6. Moving belt radiator development status

    NASA Technical Reports Server (NTRS)

    White, K. Alan

    1988-01-01

    Development of the Moving Belt Radiator (MBR) as an advanced space radiator concept is discussed. The ralative merits of Solid Belt (SBR), Liquid Belt (LBR), and Hybrid Belt (HBR) Radiators are described. Analytical and experimental efforts related to the dynamics of a rotating belt in microgravity are reviewed. The development of methods for transferring heat to the moving belt is discussed, and the results from several experimental investigations are summarized. Limited efforts related to the belt deployment and stowage, and to fabrication of a hybrid belt, are also discussed. Life limiting factors such as seal wear and micrometeroid resistance are identified. The results from various MBR point design studies for several power levels are compared with advanced Heat Pipe Radiator technology. MBR designs are shown to compare favorable at both 300 and 1000 K temperature levels. However, additional effort will be required to resolve critical technology issues and to demonstrate the advantage of MBR systems.

  7. Astronauts Gardner and Allen during loading of Westar VI in payload bay

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Joseph P. Allen IV, top, hangs onto a stinger device as Astronaut Dale A. Gardner in the cargo bay of Discovery waits to assist in the berthing of the previously stranded satellite. The end effector of the remote manipulator system (RMS), controlled from inside the Discovery'S cabin, grasps a special grapple point to Allen's right.

  8. Astronaut Andrew M. Allen, mission commander, sets up systems for a television downlink on the

    NASA Technical Reports Server (NTRS)

    1996-01-01

    STS-75 ONBOARD VIEW --- Astronaut Andrew M. Allen, mission commander, sets up systems for a television downlink on the flight deck of the Space Shuttle Columbia. Allen was joined by four other astronauts and an international payload specialist for more than 16 days of research aboard Columbia. The photograph was taken with a 70mm handheld camera.

  9. Q & A with Ed Tech Leaders: Interview with Michael W. Allen

    ERIC Educational Resources Information Center

    Shaughnessy, Michael F.

    2014-01-01

    Michael W. Allen, the Chairman and CEO of Allen Interactions, is an architect of interactive multimedia learning and is recognized for his many insights, inventions, and presentations. With over 50 years of experience in e-learning, both in academic and corporate settings, he is known for his role in creating Authorware and overseeing the work of…

  10. Allen Ivey: Pioneer in Counseling Theory and Practice, and Crusader for Multiculturalism and Social Justice

    ERIC Educational Resources Information Center

    Santiago-Rivera, Azara L.

    2009-01-01

    This article reviews the groundbreaking work of Dr. Allen Ivey through a personal interview and conversations with Mary Bradford Ivey, including a number of colleagues and former students. Allen's enormous contribution to the counseling profession spans nearly four decades. Although best known for microcounseling skills, which is widely taught in…

  11. Meeting the Challenge of Intermolecular Gold(I)-Catalyzed Cycloadditions of Alkynes and Allenes

    PubMed Central

    Muratore, Michael E; Homs, Anna; Obradors, Carla; Echavarren, Antonio M

    2014-01-01

    The development of gold(I)-catalyzed intermolecular carbo- and hetero-cycloadditions of alkynes and allenes has been more challenging than their intramolecular counterparts. Here we review, with a mechanistic perspective, the most fundamental intermolecular cycloadditions of alkynes and allenes with alkenes. PMID:25048645

  12. Nonlinear evolution of oblique whistler waves in radiation belts

    NASA Astrophysics Data System (ADS)

    Sharma, R. P.; Nandal, P.; Yadav, N.; Sharma, Swati

    2017-02-01

    Magnetic power spectrum and formation of coherent structures have been investigated in the present work applicable to Van Allen radiation belt. The nonlinear interaction of high frequency oblique whistler wave and low frequency magnetosonic wave has been investigated. Simulation was performed of the coupled equation of these two waves. The nonlinear interaction of these waves leads to the formation of the localized structures. These resulting localized structures are of complex nature. The associated magnetic power spectrum has also been studied. Dispersive nonlinear processes account for the high frequency part of the spectrum. The resulting magnetic power spectrum shows a scaling of k^{ - 4.5}. The energy transfer process from injection scales to smaller scales is explained by the results.

  13. Chapman Conference on the Earth's radiation belts and inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Baker, Daniel N.; Summers, Danny; Mann, Ian R.

    2011-10-01

    Late in the evening on 31 January 1958, a Juno (Jupiter-C) rocket blasted into space, lofting the first U.S. artificial Earth satellite into orbit. This spacecraft, dubbed Explorer 1, joined in space one other satellite, Sputnik 2, which had been launched on 3 November 1957 by the Soviet Union. The Explorer 1 mission was groundbreaking, for it carried a small scientific payload prepared at the University of Iowa by a team of researchers led by James A. Van Allen. The instrumentation on Explorer 1 (and on the subsequently successful Explorer 3) would make the first truly revolutionary discovery of the space age, namely, that Earth is enshrouded in toroids, or belts, of extraordinarily high energy, high-intensity radiation.

  14. James A. Van Allen: The Trip to Jupiter

    ERIC Educational Resources Information Center

    Jacobsen, Sally

    1973-01-01

    Discusses the research purposes and activities of the Pioneer mission, including the instruments used, data on Jupiter's radiation belt, and information about cosmic ray intensity. Included is a description of the scientist's view about the value of the space program. (CC)

  15. Radiation belts of jupiter.

    PubMed

    Fillius, R W; McIlwain, C E

    1974-01-25

    Pioneer 10 counted relativistic electrons throughout the magnetosphere of Jupiter, with the greatest fluxes being inside 20 Jupiter radii. The peak flux of electrons with energy greater than 50 million electron volts was 1.3 x 10(7) per square centimeter per second at the innermost penetration of the radiation belts.

  16. Chirality Transfer in Gold(I)‐Catalysed Hydroalkoxylation of 1,3‐Disubstituted Allenes

    PubMed Central

    Webster, Stacey; Sutherland, Daniel R.

    2016-01-01

    Abstract Gold(I)‐catalysed intermolecular hydroalkoxylation of enantioenriched 1,3‐disubstituted allenes was previously reported to occur with poor chirality transfer due to rapid allene racemisation. The first intermolecular hydroalkoxylation of allenes with efficient chirality transfer is reported here, exploiting conditions that suppress allene racemisation. A full substrate scope study reveals that excellent regio‐ and stereoselectivities are achieved when a σ‐withdrawing substituent is present. PMID:27862422

  17. Global Storm-Time Depletion of the Outer Electron Belt

    NASA Astrophysics Data System (ADS)

    Ukhorskiy, A. Y.; Sitnov, M. I.; Millan, R. M.; Kress, B. T.; Fennell, J. F.

    2014-12-01

    The outer radiation belt consists of relativistic (≳0.5 MeV) electrons trapped on closed trajectories around Earth where its magnetic field is nearly dipolar. During increased geomagnetic activity electron intensities in the belt can vary by orders of magnitude at different spatial and temporal scale. The main phase of geomagnetic storms often produces deep depletions of electron intensities over broad regions of the outer belt. Previous studies identified three possible processes that can contribute to the depletions: fully adiabatic inflation of electron drift orbits caused the ring current growth, electron loss into the atmosphere due to pitch-angle scattering by plasma waves (e.g., EMIC and whistler waves), and electron escape through the magnetopause boundary. In this paper we investigate the relative importance of the magnetopause losses to the rapid depletion of the outer belt observed at the Van Allen Probes spacecraft during the main phase of March 17, 2013 storm. The intensities of > 1 MeV electrons were depleted by more that an order of magnitude over the entire radial extent of the belt in less than 6 hours after the sudden storm commencement. For the analysis we used three-dimensional test-particle simulations of global evolution of the outer belt in the Tsyganenko-Sitnov (TS07D) magnetic field model with the inductive electric field. The comparison of the simulation results with electron measurements from the MagEIS experiment shows that the magnetopause losses in the model accounts for most of the observed depletion. The individual electron motion the process is non-adiabatic; the third invariant is violated by global variations of the inner magnetospheric fields caused by the magnetopause compressions and the buildup of ring current, while the second invariant is violated at drift orbit bifurcations. The analysis shows that the observed deep depletion of radiation belt intensities is enabled by the change in the global configuration of magnetic

  18. Ion spectral structures observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Ferradas, C.; Zhang, J.; Spence, H. E.; Kistler, L. M.; Larsen, B.; Reeves, G. D.; Skoug, R. M.; Funsten, H. O.

    2015-12-01

    During the last decades several missions have recorded the presence of dynamic spectral features of energetic ions in the inner magnetosphere. Previous studies have reported single "nose-like" structures occurring alone and simultaneous nose-like structures (up to three). These ion structures are named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. They constitute the observational signatures of ion acceleration, transport, and loss in the global magnetosphere. The HOPE mass spectrometer onboard the Van Allen Probes measures energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet, where these ion structures are observed. We present a statistical study of nose-like structures, using 2-years measurements from the HOPE instrument. The results provide important details about the spatial distribution (dependence on geocentric distance), spectral features of the structures (differences among species), and geomagnetic conditions under which these structures occur.

  19. New Cooled Feeds for the Allen Telescope Array

    NASA Astrophysics Data System (ADS)

    Welch, Wm. J.; Fleming, Matthew; Munson, Chris; Tarter, Jill; Harp, G. R.; Spencer, Robert; Wadefalk, Niklas

    2017-04-01

    We developed a new generation of low-noise, broadband feeds for the Allen Telescope Array at the Hat Creek Observatory in Northern California. The new feeds operate over the frequency range 0.9 to 14 GHz. The noise temperatures of the feeds have been substantially improved by cooling the entire feed structure as well as the low-noise amplifiers to 70 K. To achieve this improved performance, the new feeds are mounted in glass vacuum bottles with plastic lenses that maximize the microwave transmission through the bottles. Both the cooled feeds and their low-noise amplifiers produce total system temperatures that are in the range 25–30 K from 1 GHz to 5 GHz and 40–50 K up to 12.5 GHz.

  20. Trapped Proton Environment in Medium-Earth Orbit (2000-2010)

    SciTech Connect

    Chen, Yue; Friedel, Reinhard Hans; Kippen, Richard Marc

    2016-03-31

    This report describes the method used to derive fluxes of the trapped proton belt along the GPS orbit (i.e., a Medium-Earth Orbit) during 2000 – 2010, a period almost covering a solar cycle. This method utilizes a newly developed empirical proton radiation-belt model, with the model output scaled by GPS in-situ measurements, to generate proton fluxes that cover a wide range of energies (50keV- 6MeV) and keep temporal features as well. The new proton radiation-belt model is developed based upon CEPPAD proton measurements from the Polar mission (1996 – 2007). Comparing to the de-facto standard empirical model of AP8, this model is not only based upon a new data set representative of the proton belt during the same period covered by GPS, but can also provide statistical information of flux values such as worst cases and occurrence percentiles instead of solely the mean values. The comparison shows quite different results from the two models and suggests that the commonly accepted error factor of 2 on the AP8 flux output over-simplifies and thus underestimates variations of the proton belt. Output fluxes from this new model along the GPS orbit are further scaled by the ns41 in-situ data so as to reflect the dynamic nature of protons in the outer radiation belt at geomagnetically active times. Derived daily proton fluxes along the GPS ns41 orbit, whose data files are delivered along with this report, are depicted to illustrate the trapped proton environment in the Medium-Earth Orbit. Uncertainties on those daily proton fluxes from two sources are evaluated: One is from the new proton-belt model that has error factors < ~3; the other is from the in-situ measurements and the error factors could be ~ 5.

  1. On-ground Simulation of the Proton Spectrum in Space

    NASA Astrophysics Data System (ADS)

    Liu, Hai; Guan, Minchao; He, Shiyu; Yang, Dezhuang; Wang, Huaiyi; Abraimov, V. V.

    2009-01-01

    The distribution of proton energy losses in optical parts including optical lenses and mirrors was calculated using SRIM program, based on Mont Carlo method. The effect of proton energy on the optical spectrum of lenses and mirrors was also investigated through irradiation experiments, with the proton energy varying from 0.03 to 1 MeV. An approach of on-ground simulation of the proton spectrum in space was proposed taking into account the different characteristics of proton spectra in the radiation belt, solar cosmic ray, and galactic cosmic rays in GEO as well as the corresponding distribution of energy loss in optical parts.

  2. The Impenetrable Barrier Revisited - Anthroprogenic Effects on Earth's Radiation Belts

    NASA Astrophysics Data System (ADS)

    Foster, J. C.; Baker, D. N.; Erickson, P. J.; Albert, J.; Fennell, J. F.; Mishin, E. V.; Starks, M. J.; Jaynes, A. N.; Li, X.; Kanekal, S. G.; Kletzing, C.

    2015-12-01

    The Van Allen Probes are contributing significantly to the understanding of processes effecting Earth's radiation belts. It has been noted that the earthward extent of the outer zone highly-relativistic electrons encounters a nearly impenetrable barrier at a radial distance (L) near 2.8 RE inside of which they are not observed. Modeling suggests that this is the result of a balance between slow inward diffusion and hiss-induced precipitation. The large storm of 17 March 2015 afforded an excellent opportunity to investigate the impenetrable barrier using the full complement of sensors carried by the Van Allen Probes. The storm was marked by the rapid reappearance of strong fluxes of MeV electrons directly outside the barrier with the formation of very steep MeV flux gradients. In spite of the strong rapid recovery of MeV electron fluxes immediately outside the barrier, the sharpness and constancy of the gradient at the barrier is strongly suggestive of a previously unrecognized fast-acting and spatially localized mechanism responsible for the formation of such a well-defined feature during these dramatic circumstances. The Van Allen Probes regularly observe a magnetically confined bubble of VLF emissions of terrestrial origin filling the inner magnetosphere. Strongest signals are from US Navy VLF transmitters used for one-way communication to submarines. These signals largely are confined to the region of L space where their frequency is < ½ fce. The strong signal from station NAA at 24 kHz is confined to L < 2.8 where it encounters the ½ fce limit. During the event, the flux of MeV electrons decreased by 1000x across 0.5 RE outside L = 2.8 simultaneous with a 6 order of magnitude increase in the VLF wave intensity as the Probes entered the VLF bubble. The VLF transmitter frequencies are amplified at the point where they overlap natural chorus band near ½ fce suggestive of transmitter-induced triggered emissions. MeV radiation belt electrons encounter this

  3. Jupiter's radiation belts and the sweeping effect of its satellites.

    NASA Technical Reports Server (NTRS)

    Mead, G. D.; Hess, W. N.

    1973-01-01

    Jupiter's electron and proton radiation belts are analyzed, with particular reference to the sweeping effect of its five inner satellites, located deep within its magnetosphere. The characteristics of trapped electrons and protons with a magnetic moment of 50 MeV/G, considered typical at Jupiter, are calculated. The assumption is then made that a particle would be removed from the radiation belt if, in its normal motion, it would happen to impact a satellite. The mean absorption time before impact is calculated for particles located at the radial distance of each of the satellites. This average lifetime is found to be of the order of a few days. A characteristic diffusion time near each satellite was calculated, assuming violation of the third invariant due to magnetic fluctuations associated with fluctuations in the solar wind.

  4. The Role of ULF Driven Radial Transport in Rebuilding the Earth's Outer Radiation Belts

    NASA Astrophysics Data System (ADS)

    Kress, B. T.; Hudson, M. K.; Paral, J.; Selesnick, R.; Claudepierre, S. G.

    2015-12-01

    An outstanding question addressed by recent studies of the Earth's radiation belts is, what are the physical processes responsible rapid recovery of MeV electrons in the outer belt during geomagnetic storms? Rapid rebuilding of the ~1 MeV electron population near geosynchronous during periods of strongly southward IMF BZ is well modeled by computing test-particle trajectories in MHD magnetospheric model fields. The build up of ~2 MeV electrons at lower L, observed by the Van Allen Probes, is also reproduced in the test-particle model. It is not known however to what extent adiabatic transport is sufficient to produce the observed multi-MeV flux enhancements in the outer belt. By comparing observations with model results, we can determine the inward extent and high energy limit of radiation belt rebuilding due to ULF driven radial transport alone. Results from case studies of several recent geomagnetic storms occurring in conjunction with recovery of the outer radiation belts will be presented.

  5. Jupiter's radiation belts and the sweeping effect of its satellites

    NASA Technical Reports Server (NTRS)

    Mead, G. D.; Hess, W. N.

    1972-01-01

    Jupiter's electron and proton radiation belts were analyzed, with particular reference to the effect of its five inner satellites, located within its magnetosphere. The characteristics of trapped electrons and protons with a magnetic moment of 50 MeV/gauss, considered typical at Jupiter, were calculated. The mean absorption time before impact was calculated for particles located at the radial distance of each of the satellites. A characteristic diffusion time near each satellite was calculated, assuming violation of the third invariant due to magnetic fluctuations associated with fluctuations in the solar wind. This diffusion time was found to be long compared with the absorption lifetimes at Europa and Amalthea.

  6. Kuiper Belt Mapping Radar

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Nilsen, E.

    2001-01-01

    Since their initial discovery in 1992, to date only a relatively small number of Kuiper Belt Objects (KBO's) have been discovered. Current detection techniques rely on frame-to-frame comparisons of images collected by optical telescopes such as Hubble, to detect KBO's as they move against the background stellar field. Another technique involving studies of KBO's through occultation of known stars has been proposed. Such techniques are serendipitous, not systematic, and may lead to an inadequate understanding of the size, range, and distribution of KBO's. In this paper, a future Kuiper Belt Mapping Radar is proposed as a solution to the problem of mapping the size distribution, extent, and range of KBO's. This approach can also be used to recover radar albedo and object rotation rates. Additional information is contained in the original extended abstract.

  7. Jupiter's radiation belts.

    NASA Technical Reports Server (NTRS)

    Brice, N.; Mcdonough, T. R.

    1973-01-01

    A model for the production and loss of energetic electrons in Jupiter's radiation belt is presented. It is postulated that the electrons originate in the solar wind and are diffused in toward the planet by perturbations which violate the particles' third adiabatic invariant. At large distances, magnetic perturbations, electric fields associated with magnetospheric convection, or interchange instabilities driven by thermal plasma gradients may drive the diffusion. Inside about 10 Jupiter radii, the diffusion is probably driven by electric fields associated with the upper atmosphere dynamo which is driven by neutral winds in the ionosphere. The diurnal component of the dynamo wind fields produces a dawn-dusk asymmetry in the decimetric radiation from the electrons in the belts, and the lack of obvious measured asymmetries in the decimetric radiation measurements provides estimates of upper limits for these Jovian ionospheric neutral winds.

  8. The levantine amber belt

    NASA Astrophysics Data System (ADS)

    Nissenbaum, A.; Horowitz, A.

    1992-02-01

    Amber, a fossil resin, is found in Early Cretaceous sanstones and fine clastics in Lebanon, Jordan, and Israel. The term "Levantine amber belt" is coined for this amber-containing sediment belt. The amber occurs as small nodules of various colors and frequently contains inclusions of macro- and microorganisms. The Lebanese amber contains Lepidoptera and the amber from southern Israel is rich in fungal remains. The source of the amber, based on geochemical and palynological evidence, is assumed to be from a conifer belonging to the Araucariaceae. The resins were produced by trees growing in a tropical near shore environment. The amber was transported into small swamps and was preserved there together with lignite. Later reworking of those deposits resulted in redeposition of the amber in oxidized sandstones.

  9. Metamorphic belts of Anatolia

    NASA Astrophysics Data System (ADS)

    Oberhänsli, Roland; Prouteau, Amaury; Candan, Osman; Bousquet, Romain

    2015-04-01

    Investigating metamorphic rocks from high-pressure/low-temperature (HP/LT) belts that formed during the closure of several oceanic branches, building up the present Anatolia continental micro-plate gives insight to the palaeogeography of the Neotethys Ocean in Anatolia. Two coherent HP/LT metamorphic belts, the Tavşanlı Zone (distal Gondwana margin) and the Ören-Afyon-Bolkardağ Zone (proximal Gondwana margin), parallel their non-metamorphosed equivalent (the Tauride Carbonate Platform) from the Aegean coast in NW Anatolia to southern Central Anatolia. P-T conditions and timing of metamorphism in the Ören-Afyon-Bolkardağ Zone (>70?-65 Ma; 0.8-1.2 GPa/330-420°C) contrast those published for the overlying Tavşanlı Zone (88-78 Ma; 2.4 GPa/500 °C). These belts trace the southern Neotethys suture connecting the Vardar suture in the Hellenides to the Inner Tauride suture along the southern border of the Kirşehir Complex in Central Anatolia. Eastwards, these belts are capped by the Oligo-Miocene Sivas Basin. Another HP/LT metamorphic belt, in the Alanya and Bitlis regions, outlines the southern flank of the Tauride Carbonate Platform. In the Alanya Nappes, south of the Taurides, eclogites and blueschists yielded metamorphic ages around 82-80 Ma (zircon U-Pb and phengite Ar-Ar data). The Alanya-Bitlis HP belt testifies an additional suture not comparable to the northerly Tavşanlı and Ören-Afyon belts, thus implying an additional oceanic branch of the Neotethys. The most likely eastern lateral continuation of this HP belt is the Bitlis Massif, in SE Turkey. There, eclogites (1.9-2.4 GPa/480-540°C) occur within calc-arenitic meta-sediments and in gneisses of the metamorphic (Barrovian-type) basement. Zircon U-Pb ages revealed 84.4-82.4 Ma for peak metamorphism. Carpholite-bearing HP/LT metasediments representing the stratigraphic cover of the Bitlis Massif underwent 0.8-1.2 GPa/340-400°C at 79-74 Ma (Ar-Ar on white mica). These conditions compares to the Tav

  10. Deconstructing the conveyor belt.

    PubMed

    Lozier, M Susan

    2010-06-18

    For the past several decades, oceanographers have embraced the dominant paradigm that the ocean's meridional overturning circulation operates like a conveyor belt, transporting cold waters equatorward at depth and warm waters poleward at the surface. Within this paradigm, the conveyor, driven by changes in deepwater production at high latitudes, moves deep waters and their attendant properties continuously along western boundary currents and returns surface waters unimpeded to deepwater formation sites. A number of studies conducted over the past few years have challenged this paradigm by revealing the vital role of the ocean's eddy and wind fields in establishing the structure and variability of the ocean's overturning. Here, we review those studies and discuss how they have collectively changed our view of the simple conveyor-belt model.

  11. Infrared Kuiper Belt Constraints

    SciTech Connect

    Teplitz, V.L.; Stern, S.A.; Anderson, J.D.; Rosenbaum, D.; Scalise, R.J.; Wentzler, P.

    1999-05-01

    We compute the temperature and IR signal of particles of radius {ital a} and albedo {alpha} at heliocentric distance {ital R}, taking into account the emissivity effect, and give an interpolating formula for the result. We compare with analyses of {ital COBE} DIRBE data by others (including recent detection of the cosmic IR background) for various values of heliocentric distance {ital R}, particle radius {ital a}, and particle albedo {alpha}. We then apply these results to a recently developed picture of the Kuiper belt as a two-sector disk with a nearby, low-density sector (40{lt}R{lt}50{endash}90 AU) and a more distant sector with a higher density. We consider the case in which passage through a molecular cloud essentially cleans the solar system of dust. We apply a simple model of dust production by comet collisions and removal by the Poynting-Robertson effect to find limits on total and dust masses in the near and far sectors as a function of time since such a passage. Finally, we compare Kuiper belt IR spectra for various parameter values. Results of this work include: (1) numerical limits on Kuiper belt dust as a function of ({ital R}, {ital a}, {alpha}) on the basis of four alternative sets of constraints, including those following from recent discovery of the cosmic IR background by Hauser et al.; (2) application to the two-sector Kuiper belt model, finding mass limits and spectrum shape for different values of relevant parameters including dependence on time elapsed since last passage through a molecular cloud cleared the outer solar system of dust; and (3) potential use of spectral information to determine time since last passage of the Sun through a giant molecular cloud. {copyright} {ital {copyright} 1999.} {ital The American Astronomical Society}

  12. Properties of Hermean plasma belt: Numerical simulations and comparison with MESSENGER data

    NASA Astrophysics Data System (ADS)

    Herčík, David; Trávníček, Pavel M.; Å tverák, Å. těpán.; Hellinger, Petr

    2016-01-01

    Using a global hybrid model and test particle simulations we present a detailed analysis of the Hermean plasma belt structure. We investigate characteristic properties of quasi-trapped particle population characteristics and its behavior under different orientations of the interplanetary magnetic field. The plasma belt region is constantly supplied with solar wind protons via magnetospheric flanks and tail current sheet region. Protons inside the plasma belt region are quasi-trapped in the magnetic field of Mercury and perform westward drift along the planet. This region is well separated by a magnetic shell and has higher average temperatures and lower bulk proton current densities than the surrounding area. On the dayside the population exhibits loss cone distribution function matching the theoretical loss cone angle. The simulation results are in good agreement with in situ observations of MESSENGER's (MErcury Surface Space ENvironment GEochemistry, and Ranging) MAG and FIPS instruments.

  13. A simple approach to separate a mixture of homopropargylic and allenic alcohols.

    PubMed

    Fu, Fan; Hoang, Kim Le Mai; Loh, Teck-Peng

    2008-08-21

    A simple and practical approach to separate homopropargylic alcohol from allenic alcohol has been developed. It involves the formation of an insoluble silver acetylide species between silver nitrate and homopropargylic alcohol in aqueous acetone which can be separated from the allenic alcohol through a simple filtration. The homopropargylic alcohol can subsequently be recovered by hydrolysis with 1 N HCl. This protocol has been applied to the separation of a mixture of chiral homopropargylic and allenic alcohols in excellent yields with retention of absolute stereochemistry.

  14. The two last overviews by Colin Allen Wraight (1945-2014) on energy conversion in photosynthetic bacteria.

    PubMed

    Maróti, Péter; Govindjee

    2016-02-01

    Colin Allen Wraight (1945-2014) was a well-known biophysicist and biochemist of our times-formerly Professor of Biochemistry, Biophysics and Plant Biology, and Head of the Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, USA. (See a detailed Tribute to him by Govindjee et al., Photosynth Res, 2015.) During the latter part of his life, Colin had (1) given an excellent lecture in 2008 on the overall topic of the molecular mechanisms in biological energy conversion, focusing on how an ubiquinone is reduced to ubiquinol at the so-called "two electron gate", and (2) presented a review poster on the design features of long distance proton transport in biological systems, with focus on photosynthetic bacteria (a pdf file of the original is available from one of us, Govindjee). We present here for historical purpose, a complete transcript of his 2008 lecture and his 2013 poster, which have been annotated and expanded by the authors of this paper. The major theme is: electron and proton transfer in biological systems, with emphasis on bacterial reaction centers. The figures, some of which were prepared by us, are presented in sequence for both the lecture and the poster. A common bibliography is provided at the end of the paper, which is divided into two parts: (I) The Lecture; and (II) The Poster.

  15. Location of EMIC Wave Events Relative to the Plasmapause: Van Allen Probes Observations

    NASA Astrophysics Data System (ADS)

    Tetrick, S.; Engebretson, M. J.; Posch, J. L.; Kletzing, C.; Smith, C. W.; Wygant, J. R.; Gkioulidou, M.; Reeves, G. D.; Fennell, J. F.

    2015-12-01

    Many early theoretical studies of electromagnetic ion cyclotron (EMIC) waves generated in Earth's magnetosphere predicted that the equatorial plasmapause (PP) would be a preferred location for their generation. However, several large statistical studies in the past two decades, most notably Fraser and Nguyen [2001], have provided little support for this location. In this study we present a survey of the most intense EMIC waves observed by the EMFISIS fluxgate magnetometer on the Van Allen Probes-A spacecraft (with apogee at 5.9 RE) from its launch through the end of 2014, and have compared their location with simultaneous electron density data obtained by the EFW electric field instrument and ring current ion flux data obtained by the HOPE and RBSPICE instruments. We show distributions of these waves as a function of distance inside or outside the PP as a function of local time sector, frequency band (H+, He+, or both), and timing relative to magnetic storms and substorms. Most EMIC waves in this data set occurred within 1 RE of the PP in all local time sectors, but very few were limited to ± 0.1 RE, and most of these occurred in the 06-12 MLT sector during non-storm conditions. The majority of storm main phase waves in the dusk sector occurred inside the PP. He+ band waves dominated at most local times inside the PP, and H+ band waves were never observed there. Although the presence of elevated fluxes of ring current protons was common to all events, the configuration of lower energy ion populations varied as a function of geomagnetic activity and storm phase.

  16. Exploring Main Belt Asteroids

    NASA Astrophysics Data System (ADS)

    Sykes, M. V.; Larson, S. M.; Whiteley, R.; Fink, U.; Jedicke, R.; Emery, J.; Fevig, R.; Kelley, M.; Harris, A. W.; Ostro, S.; Reed, K.; Binzel, R. P.; Rivkin, A.; Magri, C.; Bottke, W.; Durda, D.; Walker, R.; Davis, D.; Hartmann, W. K.; Sears, D.; Yano, H.; Granahan, J.; Storrs, A.; Bus, S. J.; Bell, J. F.; Tholen, D.; Cellino, A.

    2001-11-01

    Terrestrial planet formation in the main asteroid belt was interrupted when growing protoplanets became sufficiently massive to gravitationally perturb the local population, causing bodies to collide with increased energy, thus ending accretion and commencing fragmentation and disruption. Few of these protoplanets are thought to have survived unshattered (e.g., Ceres, Vesta, Pallas), leaving a main belt population dominated by fragments of fragments, and significantly depleted of mass as a consequence of dynamical scattering. Yet, these fragments retain a record of the early steps of planet formation and evolution, as well as a record of early solar system conditions and the primordial composition gradient in that region. By exploring main belt asteroids through groundbased observations and spacecraft, modeling and theoretical work, we seek ultimately to recover this information. A single mission to a single target is not sufficient to address, in isolation, these questions. They require a foundation of robust, broad, and continuing groundbased, theoretical, and modeling programs. Such work is funded at a small fraction of a typical mission cost through the NASA Research and Analysis Program. Therefore, within the context of planetary decadal study recommendations to NASA, highest priority needs to be given to maintaining and growing a healthy R&A program over the next ten years and beyond. Missions also have an important role to play. An Earth orbiting remote sensing mission needs to be considered as a means of collecting important data for a large fraction of all main belt asteroids above a sub-kilometer diameter (while also realizing synergistic benefits to astrophysics). Missions to specific main belt targets can provide important new insights and leverage new understanding of existing data, models, and theories, but target definition (and corresponding instrument complement) is critical and must be based on our existing knowledge of these very diverse objects

  17. Combined convective and diffusive simulations: VERB-4D comparison with 17 March 2013 Van Allen Probes observations: VERB-4D

    SciTech Connect

    Shprits, Yuri Y.; Kellerman, Adam C.; Drozdov, Alexander Y.; Spence, Harlan E.; Reeves, Geoffrey D.; Baker, Daniel N.

    2015-11-19

    Our study focused on understanding the coupling between different electron populations in the inner magnetosphere and the various physical processes that determine evolution of electron fluxes at different energies. Observations during the 17 March 2013 storm and simulations with a newly developed Versatile Electron Radiation Belt-4D (VERB-4D) are presented. This analysis of the drift trajectories of the energetic and relativistic electrons shows that electron trajectories at transitional energies with a first invariant on the scale of ~100 MeV/G may resemble ring current or relativistic electron trajectories depending on the level of geomagnetic activity. Simulations with the VERB-4D code including convection, radial diffusion, and energy diffusion are presented. Sensitivity simulations including various physical processes show how different acceleration mechanisms contribute to the energization of energetic electrons at transitional energies. In particular, the range of energies where inward transport is strongly influenced by both convection and radial diffusion are studied. Our results of the 4-D simulations are compared to Van Allen Probes observations at a range of energies including source, seed, and core populations of the energetic and relativistic electrons in the inner magnetosphere.

  18. Plasma waves and electrostatic structures near propagating boundary layers in the inner terrestrial magnetosphere: Van Allen Probes and THEMIS observations

    NASA Astrophysics Data System (ADS)

    Malaspina, David; Wygant, John; Ergun, Robert; Reeves, Geoff; Skoug, Ruth; Larsen, Brian

    2016-10-01

    A broad range of plasma wave phenomena, only recently reported in the near-equatorial inner terrestrial magnetosphere, have been detected using the Van Allen Probes. These phenomena include electrostatic structures, such as double layers and phase space holes, as well as plasma wave modes including nonlinearly steepened whistler waves and kinetic Alfvén waves. The ubiquity of these structures is now confirmed, but it is not understood what role these structures and waves play in the dynamics of the inner magnetosphere and radiation belts. To quantify their importance, it is necessary to understand their distribution, generation, and impact on particle populations. In this study, we demonstrate a strong correlation between the occurrence of these phenomena and plasma boundaries, including the inner edge of the plasma sheet, propagating injection fronts, and the plasmapause. Further, we find that these structures and waves are continually generated as these boundaries propagate through the inner magnetosphere. Understanding the generation mechanisms of these structures and waves, as well as their impact on particle populations stands to benefit significantly from careful theoretical treatment, numerical simulation, and laboratory experiments.

  19. Van Allen Probes observations of cross-scale coupling between electromagnetic ion cyclotron waves and higher-frequency wave modes

    NASA Astrophysics Data System (ADS)

    Colpitts, C. A.; Cattell, C. A.; Engebretson, M.; Broughton, M.; Tian, S.; Wygant, J.; Breneman, A.; Thaller, S.

    2016-11-01

    We present observations of higher-frequency ( 50-2500 Hz, 0.1-0.7 fce) wave modes modulated at the frequency of colocated lower frequency (0.5-2 Hz, on the order of fci) waves. These observations come from the Van Allen Probes Electric Field and Waves instrument's burst mode data and represent the first observations of coupling between waves in these frequency ranges. The higher-frequency wave modes, typically whistler mode hiss and chorus or magnetosonic waves, last for a few to a few tens of seconds but are in some cases observed repeatedly over several hours. The higher-frequency waves are observed to be unmodulated before and after the presence of the electromagnetic ion cyclotron (EMIC) waves, but when the EMIC waves are present, the amplitude of the higher-frequency waves drops to the instrument noise level once every EMIC wave cycle. Such modulation could significantly impact wave-particle interactions such as acceleration and pitch angle scattering, which are crucial in the formation and depletion of the radiation belts. We present one case study with broadband, high-frequency waves observed to be modulated by EMIC waves repeatedly over a 2 h time span on both spacecraft. Finally, we show two additional case studies where other high-frequency wave modes exhibit similar modulation.

  20. Combined convective and diffusive simulations: VERB-4D comparison with 17 March 2013 Van Allen Probes observations: VERB-4D

    DOE PAGES

    Shprits, Yuri Y.; Kellerman, Adam C.; Drozdov, Alexander Y.; ...

    2015-11-19

    Our study focused on understanding the coupling between different electron populations in the inner magnetosphere and the various physical processes that determine evolution of electron fluxes at different energies. Observations during the 17 March 2013 storm and simulations with a newly developed Versatile Electron Radiation Belt-4D (VERB-4D) are presented. This analysis of the drift trajectories of the energetic and relativistic electrons shows that electron trajectories at transitional energies with a first invariant on the scale of ~100 MeV/G may resemble ring current or relativistic electron trajectories depending on the level of geomagnetic activity. Simulations with the VERB-4D code including convection,more » radial diffusion, and energy diffusion are presented. Sensitivity simulations including various physical processes show how different acceleration mechanisms contribute to the energization of energetic electrons at transitional energies. In particular, the range of energies where inward transport is strongly influenced by both convection and radial diffusion are studied. Our results of the 4-D simulations are compared to Van Allen Probes observations at a range of energies including source, seed, and core populations of the energetic and relativistic electrons in the inner magnetosphere.« less

  1. Lightning VLF wave propagation from source, through ionosphere to inner magnetosphere using WWLLN and Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Zheng, H.; Holzworth, R. H.; Brundell, J. B.; Wygant, J. R.; Mozer, F.; Hospodarsky, G. B.; Jacobson, A. R.; Hutchins, M. L.; Bonnell, J. W.; Breneman, A. W.; Kersten, K.

    2013-12-01

    Lightning produces strong broadband radio waves, called "sferics", which propagate in the Earth-ionosphere waveguide and are detected thousands kilometers away from their source. Global real-time detection of lightning strokes including their time, location and energy, is conducted with the World Wide Lightning Location Network (WWLLN). In the ionosphere, these sferics couple into very low frequency (VLF) whistler waves which propagate obliquely to the Earth's magnetic field. Lightning generated VLF whistler dispersion in the ionosphere has been previously observed both from thunderstorm rockets and low altitude satellites. Previous studies also show a clear match and related attenuation between sferics detected by WWLLN and VLF whistlers observed by C/NOFS satellite. This global study can now be expanded to the magnetosphere using data from the Van Allen Probes (formerly known as the Radiation Belt Storm Probes (RBSP)) with high sampling rates for vector electric and magnetic fields, and extended altitude cover from ~600km to ~5 Re above the ground. In our work, we will show the one-to-one coincidence between WWLLN sferics and RBSP VLF whistlers. This talk will explore the relationship between these one to one lightning whistler waves with stimulated emissions such as lower hybrid waves, and possible energy deposition as the large amplitude lightning whistlers propagate into the outer magnetosphere.

  2. ELF/VLF wave propagation at subauroral latitudes: Conjugate observation between the ground and Van Allen Probes A

    NASA Astrophysics Data System (ADS)

    Martinez-Calderon, Claudia; Shiokawa, Kazuo; Miyoshi, Yoshizumi; Keika, Kunihiro; Ozaki, Mitsunori; Schofield, Ian; Connors, Martin; Kletzing, Craig; Hanzelka, Miroslav; Santolik, Ondrej; Kurth, William S.

    2016-06-01

    We report simultaneous observation of ELF/VLF emissions, showing similar spectral and frequency features, between a VLF receiver at Athabasca (ATH), Canada, (L = 4.3) and Van Allen Probes A (Radiation Belt Storm Probes (RBSP) A). Using a statistical database from 1 November 2012 to 31 October 2013, we compared a total of 347 emissions observed on the ground with observations made by RBSP in the magnetosphere. On 25 February 2013, from 12:46 to 13:39 UT in the dawn sector (04-06 magnetic local time (MLT)), we observed a quasiperiodic (QP) emission centered at 4 kHz, and an accompanying short pulse lasting less than a second at 4.8 kHz in the dawn sector (04-06 MLT). RBSP A wave data showed both emissions as right-hand polarized with their Poynting vector earthward to the Northern Hemisphere. Using cross-correlation analysis, we did, for the first time, time delay analysis of a conjugate ELF/VLF event between ground and space, finding +2 to +4 s (ATH first) for the QP and -3 s (RBSP A first) for the pulse. Using backward tracing from ATH to the geomagnetic equator and forward tracing from the equator to RBSP A, based on plasmaspheric density observed by the spacecraft, we validate a possible propagation path for the QP emission which is consistent with the observed time delay.

  3. Variations of energetic electrons associated with solar wind dynamic pressure enhancement in the outer radiation belt

    NASA Astrophysics Data System (ADS)

    Lee, J.; Lee, E.; Kim, K. H.; Lee, D. H.; Lee, J.; Spence, H. E.

    2015-12-01

    Earth's outer radiation belt varies dynamically under the variations of the solar wind. In this study, we investigated the variations of energetic electrons in the outer radiation belt caused by an enhancement of the solar wind dynamic pressure associated with an interplanetary shock using the measurements from the Van Allen Probes (VAP) satellites. The enhanced dynamic pressure lasted for about 24 hours, but magnetic storm was not occurred. The impact of the interplanetary shock on 13 April 2013 produced dipolarization of the magnetic field for a few minutes, which was simultaneously observed by VAP A and B moving in the nightside region. The enhancement of the electron fluxes with E < ~600 keV coincidentally occurred during the dipolarization. Later, drift echoes with energy dispersion and ULF-like modulations were observed. By comparing the measurements from VAP A and B we will discuss spatial and temporal characteristics of the enhancement of the energetic electron fluxes.

  4. Volterra network modeling of the nonlinear finite-impulse reponse of the radiation belt flux

    SciTech Connect

    Taylor, M.; Daglis, I. A.; Anastasiadis, A.; Vassiliadis, D.

    2011-01-04

    We show how a general class of spatio-temporal nonlinear impulse-response forecast networks (Volterra networks) can be constructed from a taxonomy of nonlinear autoregressive integrated moving average with exogenous inputs (NAR-MAX) input-output equations, and used to model the evolution of energetic particle f uxes in the Van Allen radiation belts. We present initial results for the nonlinear response of the radiation belts to conditions a month earlier. The essential features of spatio-temporal observations are recovered with the model echoing the results of state space models and linear f nite impulse-response models whereby the strongest coupling peak occurs in the preceding 1-2 days. It appears that such networks hold promise for the development of accurate and fully data-driven space weather modelling, monitoring and forecast tools.

  5. Radiation Belt Storm Probes (RBSP) Education and Public Outreach Program

    NASA Astrophysics Data System (ADS)

    Turney, D.; Matiella Novak, A.; Beisser, K.; Fox, N.

    2013-11-01

    The Radiation Belt Storm Probes (RBSP) Education and Public Outreach (E/PO) program serves as a pipeline of activities to inspire and educate a broad audience about Heliophysics and the Sun-Earth system, specifically the Van Allen Radiation Belts. The program is comprised of a variety of formal, informal and public outreach activities that all align with the NASA Education Portfolio Strategic Framework outcomes. These include lesson plans and curriculum for use in the classroom, teacher workshops, internship opportunities, activities that target underserved populations, collaboration with science centers and NASA visitors' centers and partnerships with experts in the Heliophysics and education disciplines. This paper will detail the activities that make up the RBSP E/PO program, their intended audiences, and an explanation as to how they align with the NASA education outcomes. Additionally, discussions on why these activities are necessary as part of a NASA mission are included. Finally, examples of how the RBSP E/PO team has carried out some of these activities will be discussed throughout.

  6. Gold(I)-catalysed synthesis of cyclic sulfamidates by intramolecular allene hydroamination.

    PubMed

    Higginbotham, Mari C M; Bebbington, Magnus W P

    2012-08-07

    Six-membered cyclic sulfamidates are prepared in high yields by treatment of allenic sulfamates with readily available gold(I) complexes. The reaction enables formation of N-substituted quaternary centres and complements existing processes for sulfamidate formation.

  7. Meniscus root refixation technique using a modified Mason-Allen stitch.

    PubMed

    Lee, Dhong Won; Jang, Suk Hwan; Ha, Jeong Ku; Kim, Jin Goo; Ahn, Jin Hwan

    2013-03-01

    A complete posterior medial meniscus root tear results in the inability to withstand hoop stress and requires the repair of the posterior medial meniscus root. Several techniques to repair the posterior medial meniscus root have been proposed, but most techniques are based on simple stitching. A modified Mason-Allen technique, recognized as a superior stitching method to repair rotator cuff in shoulder surgery, was applied to overcome the potential weakness of those simple stitching techniques. This newly modified Mason-Allen technique reproduces the locking effect of a conventional modified Mason-Allen stitch allowing the physiological meniscal extrusion. The purpose of this article is to describe a posterior root repair technique using a modified Mason-Allen stitch with two strands consisting of a simple horizontal and a simple vertical stitch. Level of evidence V.

  8. [Book review] Green engineering: environmentally conscious design, by David T. Allen and David R. Shonnard

    USGS Publications Warehouse

    Boustany, R.G.

    2002-01-01

    Review of: Green engineering: Environmentally conscious design / David T. Allen and David R. Shonnard / Prentice-Hall, Inc., One Lake Street, Upper Saddle River, NJ 07458. 2002. 552 pages. ISBN 0-13-061908-6.

  9. THE ALLEN TELESCOPE ARRAY SEARCH FOR ELECTROSTATIC DISCHARGES ON MARS

    SciTech Connect

    Anderson, Marin M.; Siemion, Andrew P. V.; Bower, Geoffrey C.; De Pater, Imke; Barott, William C.; Delory, Gregory T.; Werthimer, Dan

    2012-01-01

    The Allen Telescope Array was used to monitor Mars between 2010 March 9 and June 2, over a total of approximately 30 hr, for radio emission indicative of electrostatic discharge. The search was motivated by the report from Ruf et al. of the detection of non-thermal microwave radiation from Mars characterized by peaks in the power spectrum of the kurtosis, or kurtstrum, at 10 Hz, coinciding with a large dust storm event on 2006 June 8. For these observations, we developed a wideband signal processor at the Center for Astronomy Signal Processing and Electronics Research. This 1024 channel spectrometer calculates the accumulated power and power-squared, from which the spectral kurtosis is calculated post-observation. Variations in the kurtosis are indicative of non-Gaussianity in the signal, which can be used to detect variable cosmic signals as well as radio frequency interference (RFI). During the three-month period of observations, dust activity occurred on Mars in the form of small-scale dust storms; however, no signals indicating lightning discharge were detected. Frequent signals in the kurtstrum that contain spectral peaks with an approximate 10 Hz fundamental were seen at both 3.2 and 8.0 GHz, but were the result of narrowband RFI with harmonics spread over a broad frequency range.

  10. SETI Observations of Exoplanets with the Allen Telescope Array

    NASA Astrophysics Data System (ADS)

    Harp, G. R.; Richards, Jon; Tarter, Jill C.; Dreher, John; Jordan, Jane; Shostak, Seth; Smolek, Ken; Kilsdonk, Tom; Wilcox, Bethany R.; Wimberly, M. K. R.; Ross, John; Barott, W. C.; Ackermann, R. F.; Blair, Samantha

    2016-12-01

    We report radio SETI observations on a large number of known exoplanets and other nearby star systems using the Allen Telescope Array (ATA). Observations were made over about 19000 hr from 2009 May to 2015 December. This search focused on narrowband radio signals from a set totaling 9293 stars, including 2015 exoplanet stars and Kepler objects of interest and an additional 65 whose planets may be close to their habitable zones. The ATA observations were made using multiple synthesized beams and an anticoincidence filter to help identify terrestrial radio interference. Stars were observed over frequencies from 1 to 9 GHz in multiple bands that avoid strong terrestrial communication frequencies. Data were processed in near-real time for narrowband (0.7-100 Hz) continuous and pulsed signals with transmitter/receiver relative accelerations from -0.3 to 0.3 m s-2. A total of 1.9 × 108 unique signals requiring immediate follow-up were detected in observations covering more than 8 × 106 star-MHz. We detected no persistent signals from extraterrestrial technology exceeding our frequency-dependent sensitivity threshold of 180-310 × 10-26 W m-2.

  11. Active and passive microwave measurements in Hurricane Allen

    NASA Technical Reports Server (NTRS)

    Delnore, V. E.; Bahn, G. S.; Grantham, W. L.; Harrington, R. F.; Jones, W. L.

    1985-01-01

    The NASA Langley Research Center analysis of the airborne microwave remote sensing measurements of Hurricane Allen obtained on August 5 and 8, 1980 is summarized. The instruments were the C-band stepped frequency microwave radiometer and the Ku-band airborne microwave scatterometer. They were carried aboard a NOAA aircraft making storm penetrations at an altitude of 3000 m and are sensitive to rain rate, surface wind speed, and surface wind vector. The wind speed is calculated from the increase in antenna brightness temperature above the estimated calm sea value. The rain rate is obtained from the difference between antenna temperature increases measured at two frequencies, and wind vector is determined from the sea surface normalized radar cross section measured at several azimuths. Comparison wind data were provided from the inertial navigation systems aboard both the C-130 aircraft at 3000 m and a second NOAA aircraft (a P-3) operating between 500 and 1500 m. Comparison rain rate data were obtained with a rain radar aboard the P-3. Evaluation of the surface winds obtained with the two microwave instruments was limited to comparisons with each other and with the flight level winds. Two important conclusions are drawn from these comparisons: (1) the radiometer is accurate when predicting flight level wind speeds and rain; and (2) the scatterometer produces well behaved and consistent wind vectors for the rain free periods.

  12. SLH Timing Belt Powertrain

    SciTech Connect

    Schneider, Abe

    2014-04-09

    The main goal of this proposal was to develop and test a novel powertrain solution for the SLH hydroEngine, a low-cost, efficient low-head hydropower technology. Nearly two-thirds of U.S. renewable electricity is produced by hydropower (EIA 2010). According to the U.S. Department of Energy; this amount could be increased by 50% with small hydropower plants, often using already-existing dams (Hall 2004). There are more than 80,000 existing dams, and of these, less than 4% generate power (Blankinship 2009). In addition, there are over 800 irrigation districts in the U.S., many with multiple, non-power, low-head drops. These existing, non-power dams and irrigation drops could be retrofitted to produce distributed, baseload, renewable energy with appropriate technology. The problem is that most existing dams are low-head, or less than 30 feet in height (Ragon 2009). Only about 2% of the available low-head hydropower resource in the U.S. has been developed, leaving more than 70 GW of annual mean potential low-head capacity untapped (Hall 2004). Natel Energy, Inc. is developing a low-head hydropower turbine that operates efficiently at heads less than 6 meters and is cost-effective for deployment across multiple low-head structures. Because of the unique racetrack-like path taken by the prime-movers in the SLH, a flexible powertrain is required. Historically, the only viable technological solution was roller chain. Despite the having the ability to easily attach blades, roller chain is characterized by significant drawbacks, including high cost, wear, and vibration from chordal action. Advanced carbon- fiber-reinforced timing belts have been recently developed which, coupled with a novel belt attachment system developed by Natel Energy, result in a large reduction in moving parts, reduced mass and cost, and elimination of chordal action for increased fatigue life. The work done in this project affirmatively addressed each of the following 3 major uncertainties concerning

  13. STS-46 Pilot Allen uses cycle ergometer on OV-104's middeck

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-46 Pilot Andrew M. Allen exercises using the cycle ergometer on the middeck of Atlantis, Orbiter Vehicle (OV) 104. Allen, shirtless, is equipped with sensors for monitoring his biological systems during the exercise session. A communications kit assembly cable freefloats from his headset at his right and in front of the forward lockers. The open airlock hatch appears at his left and the sleep station behind him.

  14. Astronauts Gardner and Allen bringing Westar VI satellite into payload bay

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Dale A. Gardner, left, and Joseph P. Allen IV work together with Dr. Anna L. Fisher (in the Discovery controlling the remote manipulator system (RMS) arm) to bring the Westar VI satellite into the Discovery's payload bay. Allen is on a mobile foot restraint, which is attached to the RMS end effector. Gardner uses the manned maneuvering unit (MMU) on the other side of the satellite. He is attempting to remove the stinger device from the now stabilized satellite.

  15. Enantioselective Terminal Addition to Allenes by Dual Chiral Primary Amine/Palladium Catalysis.

    PubMed

    Zhou, Han; Wang, Yaning; Zhang, Long; Cai, Mao; Luo, Sanzhong

    2017-03-15

    We herein describe a synergistic chiral primary amine/achiral palladium catalyzed enantioselective terminal addition to allenes with α-branched β-ketocarbonyls and aldehydes. The reactions afford allylic adducts bearing acyclic all-carbon quaternary centers with high regio- and enantioselectivity. A wide range of allenes including those aliphatic or 1,1'-disubstituted could be employed, thus expanding the scope of typical asymmetric allylic alkylation reactions.

  16. Microwave-promoted synthesis of bicyclic azocine-β-lactams from bis(allenes).

    PubMed

    Alcaide, Benito; Almendros, Pedro; Aragoncillo, Cristina; Fernández, Israel; Gómez-Campillos, Gonzalo

    2014-08-01

    A metal-free preparation of structurally novel bicyclic azocine-β-lactams has been developed. The first examples accounting for the preparation of eight-membered rings from bis(allenes) in the absence of metals have been achieved by the thermolysis of nonconjugated 2-azetidinone-tethered bis(allenes) on application of microwave irradiation. This selective carbocyclization reaction has been studied experimentally, and additionally, its mechanism has been investigated by a DFT study.

  17. STS-46 Pilot Allen, in LES, at pilots station on OV-104's forward flight deck

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-46 Pilot Andrew M. Allen, wearing launch and entry suit (LES) and launch and entry helmet (LEH), reviews descent procedural checklists while at pilots station on the forward flight deck of Atlantis, Orbiter Vehicle (OV) 104. The head-up display (HUD), flight mirror assembly, and forward windows appear in front of Allen. Control panels with drinking water containers and checklists are seen overhead.

  18. Proton Transport

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    The transport of protons across membranes is an essential process for both bioenergetics of modern cells and the origins of cellular life. All living systems make use of proton gradients across cell walls to convert environmental energy into a high-energy chemical compound, adenosine triphosphate (ATP), synthesized from adenosine diphosphate. ATP, in turn, is used as a source of energy to drive many cellular reactions. The ubiquity of this process in biology suggests that even the earliest cellular systems were relying on proton gradient for harvesting environmental energy needed to support their survival and growth. In contemporary cells, proton transfer is assisted by large, complex proteins embedded in membranes. The issue addressed in this Study was: how the same process can be accomplished with the aid of similar but much simpler molecules that could have existed in the protobiological milieu? The model system used in the study contained a bilayer membrane made of phospholipid, dimyristoylphosphatidylcholine (DMPC) which is a good model of the biological membranes forming cellular boundaries. Both sides of the bilayer were surrounded by water which simulated the environment inside and outside the cell. Embedded in the membrane was a fragment of the Influenza-A M$_2$ protein and enough sodium counterions to maintain system neutrality. This protein has been shown to exhibit remarkably high rates of proton transport and, therefore, is an excellent model to study the formation of proton gradients across membranes. The Influenza M$_2$ protein is 97 amino acids in length, but a fragment 25 amino acids long. which contains a transmembrane domain of 19 amino acids flanked by three amino acids on each side. is sufficient to transport protons. Four identical protein fragments, each folded into a helix, aggregate to form small channels spanning the membrane. Protons are conducted through a narrow pore in the middle of the channel in response to applied voltage. This

  19. Radiation Belt Dynamics

    DTIC Science & Technology

    2015-12-27

    is unlimited. 15 DISTRIBUTION LIST DTIC/OCP 8725 John J. Kingman Rd, Suite 0944 Ft Belvoir, VA 22060-6218 1 cy AFRL /RVIL Kirtland AFB, NM 87117... AFRL -RV-PS- AFRL -RV-PS- TR-2016-0007 TR-2016-0007 RADIATION BELT DYNAMICS Jay M. Albert, et al. 27 December 2015 Final Report APPROVED FOR... KIRTLAND AIR FORCE BASE, NM 87117-5776 DTIC COPY NOTICE AND SIGNATURE PAGE Using Government drawings, specifications, or other data included in this

  20. Geographical variation in bill size across bird species provides evidence for Allen's rule.

    PubMed

    Symonds, Matthew R E; Tattersall, Glenn J

    2010-08-01

    Allen's rule proposes that the appendages of endotherms are smaller, relative to body size, in colder climates, in order to reduce heat loss. Empirical support for Allen's rule is mainly derived from occasional reports of geographical clines in extremity size of individual species. Interspecific evidence is restricted to two studies of leg proportions in seabirds and shorebirds. We used phylogenetic comparative analyses of 214 bird species to examine whether bird bills, significant sites of heat exchange, conform to Allen's rule. The species comprised eight diverse taxonomic groups-toucans, African barbets, Australian parrots, estrildid finches, Canadian galliforms, penguins, gulls, and terns. Across all species, there were strongly significant relationships between bill length and both latitude and environmental temperature, with species in colder climates having significantly shorter bills. Patterns supporting Allen's rule in relation to latitudinal or altitudinal distribution held within all groups except the finches. Evidence for a direct association with temperature was found within four groups (parrots, galliforms, penguins, and gulls). Support for Allen's rule in leg elements was weaker, suggesting that bird bills may be more susceptible to thermoregulatory constraints generally. Our results provide the strongest comparative support yet published for Allen's rule and demonstrate that thermoregulation has been an important factor in shaping the evolution of bird bills.

  1. Saturn Neutron Exosphere as Source for Inner and Innermost Radiation Belts

    NASA Technical Reports Server (NTRS)

    Cooper, John; Lipatov, Alexander; Sittler, Edward; Sturner, Steven

    2011-01-01

    Energetic proton and electron measurements by the ongoing Cassini orbiter mission are expanding our knowledge of the highest energy components of the Saturn magnetosphere in the inner radiation belt region after the initial discoveries of these belts by the Pioneer 11 and Voyager 2 missions. Saturn has a neutron exosphere that extends throughout the magnetosphere from the cosmic ray albedo neutron source at the planetary main rings and atmosphere. The neutrons emitted from these sources at energies respectively above 4 and 8 eV escape the Saturn system, while those at lower energies are gravitationally bound. The neutrons undergo beta decay in average times of about 1000 seconds to provide distributed sources of protons and electrons throughout Saturn's magnetosphere with highest injection rates close to the Saturn and ring sources. The competing radiation belt source for energetic electrons is rapid inward diffusion and acceleration of electrons from the middle magnetosphere and beyond. Minimal losses during diffusive transport across the moon orbits, e.g. of Mimas and Enceladus, and local time asymmetries in electron intensity, suggest that drift resonance effects preferentially boost the diffusion rates of electrons from both sources. Energy dependences of longitudinal gradient-curvature drift speeds relative to the icy moons are likely responsible for hemispheric differences (e.g., Mimas, Tethys) in composition and thermal properties as at least partly produced by radiolytic processes. A continuing mystery is the similar radial profiles of lower energy (<10 MeV) protons in the inner belt region. Either the source of these lower energy protons is also neutron decay, but perhaps alternatively from atmospheric albedo, or else all protons from diverse distributed sources are similarly affected by losses at the moon' orbits, e.g. because the proton diffusion rates are extremely low. Enceladus cryovolcanism, and radiolytic processing elsewhere on the icy moon and

  2. MeV proton flux predictions near Saturn's D ring.

    PubMed

    Kollmann, P; Roussos, E; Kotova, A; Cooper, J F; Mitchell, D G; Krupp, N; Paranicas, C

    2015-10-01

    Radiation belts of MeV protons have been observed just outward of Saturn's main rings. During the final stages of the mission, the Cassini spacecraft will pass through the gap between the main rings and the planet. Based on how the known radiation belts of Saturn are formed, it is expected that MeV protons will be present in this gap and also bounce through the tenuous D ring right outside the gap. At least one model has suggested that the intensity of MeV protons near the planet could be much larger than in the known belts. We model this inner radiation belt using a technique developed earlier to understand Saturn's known radiation belts. We find that the inner belt is very different from the outer belts in the sense that its intensity is limited by the densities of the D ring and Saturn's upper atmosphere, not by radial diffusion and satellite absorption. The atmospheric density is relatively well constrained by EUV occultations. Based on that we predict an intensity in the gap region that is well below that of the known belts. It is more difficult to do the same for the region magnetically connected to the D ring since its density is poorly constrained. We find that the intensity in this region can be comparable to the known belts. Such intensities pose no hazard to the mission since Cassini would only experience these fluxes on timescales of minutes but might affect scientific measurements by decreasing the signal-to-contamination ratio of instruments.

  3. MeV proton flux predictions near Saturn's D ring

    NASA Astrophysics Data System (ADS)

    Kollmann, P.; Roussos, E.; Kotova, A.; Cooper, J. F.; Mitchell, D. G.; Krupp, N.; Paranicas, C.

    2015-10-01

    Radiation belts of MeV protons have been observed just outward of Saturn's main rings. During the final stages of the mission, the Cassini spacecraft will pass through the gap between the main rings and the planet. Based on how the known radiation belts of Saturn are formed, it is expected that MeV protons will be present in this gap and also bounce through the tenuous D ring right outside the gap. At least one model has suggested that the intensity of MeV protons near the planet could be much larger than in the known belts. We model this inner radiation belt using a technique developed earlier to understand Saturn's known radiation belts. We find that the inner belt is very different from the outer belts in the sense that its intensity is limited by the densities of the D ring and Saturn's upper atmosphere, not by radial diffusion and satellite absorption. The atmospheric density is relatively well constrained by EUV occultations. Based on that we predict an intensity in the gap region that is well below that of the known belts. It is more difficult to do the same for the region magnetically connected to the D ring since its density is poorly constrained. We find that the intensity in this region can be comparable to the known belts. Such intensities pose no hazard to the mission since Cassini would only experience these fluxes on timescales of minutes but might affect scientific measurements by decreasing the signal-to-contamination ratio of instruments.

  4. Geography of the asteroid belt

    NASA Technical Reports Server (NTRS)

    Zellner, B. H.

    1978-01-01

    The CSM classification serves as the starting point on the geography of the asteroid belt. Raw data on asteroid types are corrected for observational biases (against dark objects, for instance) to derive the distribution of types throughout the belt. Recent work on family members indicates that dynamical families have a true physical relationship, presumably indicating common origin in the breakup of a parent asteroid.

  5. Physics and Automobile Safety Belts.

    ERIC Educational Resources Information Center

    Kortman, Peter; Witt, C. Edwin

    This collection of problems and experiments related to automobile safety belt usage is intended to serve as a supplement to a standard physics course. Its purpose is to convince the students that the use of safety belts to prevent injury or death is firmly supported by the considerations of physical quantities and laws which apply in a collision…

  6. Teaching Science: Seat Belt Science.

    ERIC Educational Resources Information Center

    Leyden, Michael B.

    1994-01-01

    Describes activities that will help students understand how car seat belts work, the limited reaction time available to passengers in an automobile accident, and the force of impact in a car collision. These activities will provide students with hands-on experiences that demonstrate the importance of always wearing seat belts while in an…

  7. Proton Therapy

    MedlinePlus

    ... effects of the treatment. top of page What equipment is used? Proton beam therapy uses special machines, ... tumor cells. top of page Who operates the equipment? With backgrounds in mechanical, electrical, software, hardware and ...

  8. 76 FR 36318 - Safety Zone; Waterway Closure, Morgan City-Port Allen Route From Mile Marker 0 to Port Allen Lock

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-22

    ... and tows from destruction, loss or injury due to hazards associated with rising flood water. DATES... the general public, levee system, vessels and tows from the hazards associated with rising flood water... hazards associated with rising flood water on the Morgan City-Port Allen Route. Basis and Purpose...

  9. The Relativistic Proton Spectrometer (RPS) Online Data Products

    NASA Astrophysics Data System (ADS)

    Mazur, J. E.; O'Brien, P. P.; Mazur, E.; Redding, M.; McNab, M. C.; Sorensen, G.; Weigel, R. S.

    2012-12-01

    We present a tutorial on the Relativistic Proton Spectrometer (RPS) on-ine data products. RPS measures protons with energies from 60 MeV to over 1 GeV aboard the NASA Radiation Belt Storm Probes mission. The RPS data products are hosted by the Virtual Radiation Belt Observatory (ViRBO), and make extensive use of ViRBO data visualization and organization tools, including Autoplot. We will provide a hands-on demonstration of the website and data browsing capabilities provided by ViRBO.

  10. Reanalysis and forecasting killer electrons in Earth's radiation belts using the VERB code

    NASA Astrophysics Data System (ADS)

    Kellerman, Adam; Kondrashov, Dmitri; Shprits, Yuri; Podladchikova, Tatiana; Drozdov, Alexander

    2016-07-01

    The Van Allen radiation belts are torii-shaped regions of trapped energetic particles, that in recent years, have become a principle focus for satellite operators and engineers. During geomagnetic storms, electrons can be accelerated up to relativistic energies, where they may penetrate spacecraft shielding and damage electrical systems, causing permanent damage or loss of spacecraft. Data-assimilation provides an optimal way to combine observations of the radiation belts with a physics-based model in order to more accurately specify the global state of the Earth's radiation belts. We present recent advances to the data-assimilative version of the Versatile Electron Radiation Belt (VERB) code, including more sophisticated error analysis, and incorporation of realistic field-models to more accurately specify fluxes at a given MLT or along a spacecraft trajectory. The effect of recent stream-interaction-region (SIR) driven enhancements are investigated using the improved model. We also present a real-time forecast model based on the data-assimilative VERB code, and discuss the forecast performance over the past 12 months.

  11. Understanding the Dynamical Evolution of the Earth Radiation Belt and Ring Current Coupled System

    NASA Astrophysics Data System (ADS)

    Shprits, Yuri; Usanova, Maria; Kellerman, Adam; Drozdov, Alexander

    2016-07-01

    Modeling and understanding the ring current and radiation belt-coupled system has been a grand challenge since the beginning of the space age. In this study we show long-term simulations with a 3D Versatile Electron Radiation Belt (VERB) code of modeling the radiation belts with boundary conditions derived from observations around geosynchronous orbit. Simulations can reproduce long term variations of the electron radiation belt fluxes and show the importance of local acceleration, radial diffusion, loss to the atmosphere and loss to the magnetopause. We also present 4D VERB simulations that include convective transport, radial diffusion, pitch angle scattering and local acceleration. VERB simulations show that the lower energy inward transport is dominated by the convection and higher energy transport is dominated by the diffusive radial transport. We also show that at energies of 100s of keV, a number of processes work simultaneously, including convective transport, radial diffusion, local acceleration, loss to the loss cone and loss to the magnetopause. The results of the simulation of the March 2013 storm are compared with Van Allen Probes observations.

  12. Reproducing the observed energy-dependent structure of Earth's electron radiation belts during storm recovery with an event-specific diffusion model

    DOE PAGES

    Ripoll, J. -F.; Reeves, Geoffrey D.; Cunningham, Gregory Scott; ...

    2016-06-11

    Here, we present dynamic simulations of energy-dependent losses in the radiation belt “slot region” and the formation of the two-belt structure for the quiet days after the 1 March storm. The simulations combine radial diffusion with a realistic scattering model, based data-driven spatially and temporally resolved whistler-mode hiss wave observations from the Van Allen Probes satellites. The simulations reproduce Van Allen Probes observations for all energies and L shells (2–6) including (a) the strong energy dependence to the radiation belt dynamics (b) an energy-dependent outer boundary to the inner zone that extends to higher L shells at lower energies andmore » (c) an “S-shaped” energy-dependent inner boundary to the outer zone that results from the competition between diffusive radial transport and losses. We find that the characteristic energy-dependent structure of the radiation belts and slot region is dynamic and can be formed gradually in ~15 days, although the “S shape” can also be reproduced by assuming equilibrium conditions. The highest-energy electrons (E > 300 keV) of the inner region of the outer belt (L ~ 4–5) also constantly decay, demonstrating that hiss wave scattering affects the outer belt during times of extended plasmasphere. Through these simulations, we explain the full structure in energy and L shell of the belts and the slot formation by hiss scattering during storm recovery. We show the power and complexity of looking dynamically at the effects over all energies and L shells and the need for using data-driven and event-specific conditions.« less

  13. Reproducing the observed energy-dependent structure of Earth's electron radiation belts during storm recovery with an event-specific diffusion model

    SciTech Connect

    Ripoll, J. -F.; Reeves, Geoffrey D.; Cunningham, Gregory Scott; Loridan, V.; Denton, M.; Santolik, O.; Kurth, W. S.; Kletzing, C. A.; Turner, D. L.; Henderson, M. G.; Ukhorskiy, A. Y.

    2016-06-11

    Here, we present dynamic simulations of energy-dependent losses in the radiation belt “slot region” and the formation of the two-belt structure for the quiet days after the 1 March storm. The simulations combine radial diffusion with a realistic scattering model, based data-driven spatially and temporally resolved whistler-mode hiss wave observations from the Van Allen Probes satellites. The simulations reproduce Van Allen Probes observations for all energies and L shells (2–6) including (a) the strong energy dependence to the radiation belt dynamics (b) an energy-dependent outer boundary to the inner zone that extends to higher L shells at lower energies and (c) an “S-shaped” energy-dependent inner boundary to the outer zone that results from the competition between diffusive radial transport and losses. We find that the characteristic energy-dependent structure of the radiation belts and slot region is dynamic and can be formed gradually in ~15 days, although the “S shape” can also be reproduced by assuming equilibrium conditions. The highest-energy electrons (E > 300 keV) of the inner region of the outer belt (L ~ 4–5) also constantly decay, demonstrating that hiss wave scattering affects the outer belt during times of extended plasmasphere. Through these simulations, we explain the full structure in energy and L shell of the belts and the slot formation by hiss scattering during storm recovery. We show the power and complexity of looking dynamically at the effects over all energies and L shells and the need for using data-driven and event-specific conditions.

  14. Evaluation of the static belt fit provided by belt-positioning booster seats.

    PubMed

    Reed, Matthew P; Ebert, Sheila M; Sherwood, Christopher P; Klinich, Kathleen D; Manary, Miriam A

    2009-05-01

    Belt-positioning booster seats are recommended for children who use vehicle seat belts as primary restraints but who are too small to obtain good belt fit. Previous research has shown that belt-positioning boosters reduce injury risk, but the belt fit produced by the wide range of boosters in the US market has not previously been assessed. The present study describes the development of a method for quantifying static belt fit with a Hybrid-III 6-year-old test dummy. The measurement method was applied in a laboratory seat mockup to 31 boosters (10 in both backless and highback modes) across a range of belt geometries obtained from in-vehicle measurements. Belt fit varied widely across boosters. Backless boosters generally produced better lap belt fit than highback boosters, largely because adding the back component moved the dummy forward with respect to the lap belt routing guides. However, highback boosters produced more consistent shoulder belt fit because of the presence of belt routing guides near the shoulder. Some boosters performed well on both lap belt and shoulder belt fit. Lap belt fit in dedicated boosters was generally better than in combination restraints that also can be used with an integrated harness. Results demonstrate that certain booster design features produce better belt fit across a wide range of belt geometries. Lap belt guides that hold the belt down, rather than up, and shoulder belt guides integrated into the booster backrest provided better belt fit.

  15. Allen Brain Atlas: an integrated spatio-temporal portal for exploring the central nervous system

    PubMed Central

    Sunkin, Susan M.; Ng, Lydia; Lau, Chris; Dolbeare, Tim; Gilbert, Terri L.; Thompson, Carol L.; Hawrylycz, Michael; Dang, Chinh

    2013-01-01

    The Allen Brain Atlas (http://www.brain-map.org) provides a unique online public resource integrating extensive gene expression data, connectivity data and neuroanatomical information with powerful search and viewing tools for the adult and developing brain in mouse, human and non-human primate. Here, we review the resources available at the Allen Brain Atlas, describing each product and data type [such as in situ hybridization (ISH) and supporting histology, microarray, RNA sequencing, reference atlases, projection mapping and magnetic resonance imaging]. In addition, standardized and unique features in the web applications are described that enable users to search and mine the various data sets. Features include both simple and sophisticated methods for gene searches, colorimetric and fluorescent ISH image viewers, graphical displays of ISH, microarray and RNA sequencing data, Brain Explorer software for 3D navigation of anatomy and gene expression, and an interactive reference atlas viewer. In addition, cross data set searches enable users to query multiple Allen Brain Atlas data sets simultaneously. All of the Allen Brain Atlas resources can be accessed through the Allen Brain Atlas data portal. PMID:23193282

  16. Allen Brain Atlas: an integrated spatio-temporal portal for exploring the central nervous system.

    PubMed

    Sunkin, Susan M; Ng, Lydia; Lau, Chris; Dolbeare, Tim; Gilbert, Terri L; Thompson, Carol L; Hawrylycz, Michael; Dang, Chinh

    2013-01-01

    The Allen Brain Atlas (http://www.brain-map.org) provides a unique online public resource integrating extensive gene expression data, connectivity data and neuroanatomical information with powerful search and viewing tools for the adult and developing brain in mouse, human and non-human primate. Here, we review the resources available at the Allen Brain Atlas, describing each product and data type [such as in situ hybridization (ISH) and supporting histology, microarray, RNA sequencing, reference atlases, projection mapping and magnetic resonance imaging]. In addition, standardized and unique features in the web applications are described that enable users to search and mine the various data sets. Features include both simple and sophisticated methods for gene searches, colorimetric and fluorescent ISH image viewers, graphical displays of ISH, microarray and RNA sequencing data, Brain Explorer software for 3D navigation of anatomy and gene expression, and an interactive reference atlas viewer. In addition, cross data set searches enable users to query multiple Allen Brain Atlas data sets simultaneously. All of the Allen Brain Atlas resources can be accessed through the Allen Brain Atlas data portal.

  17. Three-dimensional data assimilation and reanalysis of radiation belt electrons: Observations over two solar cycles, and operational forecasting.

    NASA Astrophysics Data System (ADS)

    Kellerman, A. C.; Shprits, Y.; Kondrashov, D. A.; Podladchikova, T.; Drozdov, A.; Subbotin, D.; Makarevich, R. A.; Donovan, E.; Nagai, T.

    2015-12-01

    Understanding of the dynamics in Earth's radiation belts is critical to accurate modeling and forecasting of space weather conditions, both which are important for design, and protection of our space-borne assets. In the current study, we utilize the Versatile Electron Radiation Belt (VERB) code, multi-spacecraft measurements, and a split-operator Kalman filter to recontructe the global state of the radiation belt system in the CRRES era and the current era. The reanalysis has revealed a never before seen 4-belt structure in the radiation belts during the March 1991 superstorm, and highlights several important aspects in regards to the the competition between the source, acceleration, loss, and transport of particles. In addition to the above, performing reanalysis in adiabatic coordinates relies on specification of the Earth's magnetic field, and associated observational, and model errors. We determine the observational errors for the Kalman filter directly from cross-spacecraft phase-space density (PSD) conjunctions, and obtain the error in VERB by comparison with reanalysis over a long time period. Specification of errors associated with several magnetic field models provides an important insight into the applicability of such models for radiation belt research. The comparison of CRRES area reanalysis with Van Allen Probe era reanalysis allows us to perform a global comparison of the dynamics of the radiation belts during different parts of the solar cycle and during different solar cycles. The data assimilative model is presently used to perform operational forecasts of the radiation belts (http://rbm.epss.ucla.edu/realtime-forecast/).

  18. Characterization of radiation belt electron energy spectra from CRRES observations

    NASA Astrophysics Data System (ADS)

    Johnston, W. R.; Lindstrom, C. D.; Ginet, G. P.

    2010-12-01

    Energetic electrons in the outer radiation belt and the slot region exhibit a wide variety of energy spectral forms, more so than radiation belt protons. We characterize the spatial and temporal dependence of these forms using observations from the CRRES satellite Medium Electron Sensor A (MEA) and High-Energy Electron Fluxmeter (HEEF) instruments, together covering an energy range 0.15-8 MeV. Spectra were classified with two independent methods, data clustering and curve-fitting analyses, in each case defining categories represented by power law, exponential, and bump-on-tail (BOT) or other complex shapes. Both methods yielded similar results, with BOT, exponential, and power law spectra respectively dominating in the slot region, outer belt, and regions just beyond the outer belt. The transition from exponential to power law spectra occurs at higher L for lower magnetic latitude. The location of the transition from exponential to BOT spectra is highly correlated with the location of the plasmapause. In the slot region during the days following storm events, electron spectra were observed to evolve from exponential to BOT yielding differential flux minima at 350-650 keV and maxima at 1.5-2 MeV; such evolution has been attributed to energy-dependent losses from scattering by whistler hiss.

  19. Evaluation of the new radiation belt AE9/AP9/SPM model for a cislunar mission

    NASA Astrophysics Data System (ADS)

    Badavi, Francis F.; Walker, Steven A.; Santos Koos, Lindsey M.

    2014-09-01

    Space mission planners continue to experience challenges associated with human space flight. Concerned with the omnipresence of harmful ionizing radiation in space, at the mission design stage, mission planners must evaluate the amount of exposure the crew of a spacecraft is subjected to during the transit trajectory from low Earth orbit (LEO) to geosynchronous orbit (GEO) and beyond (free space). The Earth's geomagnetic field is located within the domain of LEO-GEO and, depending on latitude, extends out some 40,000-60,000 km. This field contains the Van Allen trapped electrons, protons, and low-energy plasmas, such as the nuclei of hydrogen, helium, oxygen, and to a lesser degree other atoms. In addition, there exist the geomagnetically attenuated energetic galactic cosmic rays (GCR). These particles are potentially harmful to improperly shielded crew members and onboard subsystems. Mitigation strategies to limit the exposure due to free space GCR and sporadic solar energetic particles (SEP) such as flare and coronal mass ejection (CME) must also be exercised beyond the trapped field. Presented in this work is the exposure analysis for a multi-vehicle mission planned for the epoch of February 2020 from LEO to the Earth-moon Lagrange-point two (L2), located approximately 63,000 km beyond the orbit of the Earth-moon binary system. Space operation at L2 provides a gravitationally stable orbit for a vehicle and partially eliminates the need for periodic thrust-vectoring to maintain orbital stability. In the cislunar (Earth-moon) space of L2, the mission trajectory and timeline in this work call for a cargo vehicle to rendezvous with a crew vehicle. This is followed by 15 days of space activities at L2 while the cargo and crew vehicles are docked after which the crew returns to Earth. The mission epoch of 2020 is specifically chosen as it is anticipated that the next solar minimum (i.e. end of cycle 24) in the Sun's approximate 11 years cycle will take place around

  20. Investigation of a new type charging belt

    SciTech Connect

    Jones, N.L.

    1994-12-31

    There are many desirable characteristics for an electrostatic accelerator charging belt. An attempt has been made to find a belt that improves on these properties over the stock belt. Results of the search, procurement, and 1,500 hours of operational experience with a substantially different belt are reported.

  1. Seat Belt Use and Stress in Adolescents.

    ERIC Educational Resources Information Center

    Schichor, Aric; And Others

    1990-01-01

    Explored adolescent seat belt use and psychosocial risk factors in urban minority population (n=541). Found seat belt use reported by 49 percent of respondents. Those reporting no or intermittent seat belt use were significantly more likely than seat belt users to feel down, have decreased home support, have problems with school and the law, and…

  2. Whistler anisotropy instabilities as the source of banded chorus: Van Allen Probes observations and particle-in-cell simulations.

    PubMed

    Fu, Xiangrong; Cowee, Misa M; Friedel, Reinhard H; Funsten, Herbert O; Gary, S Peter; Hospodarsky, George B; Kletzing, Craig; Kurth, William; Larsen, Brian A; Liu, Kaijun; MacDonald, Elizabeth A; Min, Kyungguk; Reeves, Geoffrey D; Skoug, Ruth M; Winske, Dan

    2014-10-01

    Magnetospheric banded chorus is enhanced whistler waves with frequencies ωr <Ω e , where Ω e is the electron cyclotron frequency, and a characteristic spectral gap at ωr ≃Ω e /2. This paper uses spacecraft observations and two-dimensional particle-in-cell simulations in a magnetized, homogeneous, collisionless plasma to test the hypothesis that banded chorus is due to local linear growth of two branches of the whistler anisotropy instability excited by two distinct, anisotropic electron components of significantly different temperatures. The electron densities and temperatures are derived from Helium, Oxygen, Proton, and Electron instrument measurements on the Van Allen Probes A satellite during a banded chorus event on 1 November 2012. The observations are consistent with a three-component electron model consisting of a cold (a few tens of eV) population, a warm (a few hundred eV) anisotropic population, and a hot (a few keV) anisotropic population. The simulations use plasma and field parameters as measured from the satellite during this event except for two numbers: the anisotropies of the warm and the hot electron components are enhanced over the measured values in order to obtain relatively rapid instability growth. The simulations show that the warm component drives the quasi-electrostatic upper band chorus and that the hot component drives the electromagnetic lower band chorus; the gap at ∼Ω e /2 is a natural consequence of the growth of two whistler modes with different properties.

  3. Whistler anisotropy instabilities as the source of banded chorus: Van Allen Probes observations and particle-in-cell simulations

    NASA Astrophysics Data System (ADS)

    Fu, Xiangrong; Cowee, Misa M.; Friedel, Reinhard H.; Funsten, Herbert O.; Gary, S. Peter; Hospodarsky, George B.; Kletzing, Craig; Kurth, William; Larsen, Brian A.; Liu, Kaijun; MacDonald, Elizabeth A.; Min, Kyungguk; Reeves, Geoffrey D.; Skoug, Ruth M.; Winske, Dan

    2014-10-01

    Magnetospheric banded chorus is enhanced whistler waves with frequencies ωr<Ωe, where Ωe is the electron cyclotron frequency, and a characteristic spectral gap at ωr≃Ωe/2. This paper uses spacecraft observations and two-dimensional particle-in-cell simulations in a magnetized, homogeneous, collisionless plasma to test the hypothesis that banded chorus is due to local linear growth of two branches of the whistler anisotropy instability excited by two distinct, anisotropic electron components of significantly different temperatures. The electron densities and temperatures are derived from Helium, Oxygen, Proton, and Electron instrument measurements on the Van Allen Probes A satellite during a banded chorus event on 1 November 2012. The observations are consistent with a three-component electron model consisting of a cold (a few tens of eV) population, a warm (a few hundred eV) anisotropic population, and a hot (a few keV) anisotropic population. The simulations use plasma and field parameters as measured from the satellite during this event except for two numbers: the anisotropies of the warm and the hot electron components are enhanced over the measured values in order to obtain relatively rapid instability growth. The simulations show that the warm component drives the quasi-electrostatic upper band chorus and that the hot component drives the electromagnetic lower band chorus; the gap at ˜Ωe/2 is a natural consequence of the growth of two whistler modes with different properties.

  4. Simulations of inner magnetosphere dynamics with an expanded RAM-SCB model and comparisons with Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Jordanova, V. K.; Yu, Y.; Niehof, J. T.; Skoug, R. M.; Reeves, G. D.; Kletzing, C. A.; Fennell, J. F.; Spence, H. E.

    2014-04-01

    Simulations from our newly expanded ring current-atmosphere interactions model with self-consistent magnetic field (RAM-SCB), now valid out to 9 RE, are compared for the first time with Van Allen Probes observations. The expanded model reproduces the storm time ring current buildup due to the increased convection and inflow of plasma from the magnetotail. It matches Magnetic Electron Ion Spectrometer (MagEIS) observations of the trapped high-energy (>50 keV) ion flux; however, it underestimates the low-energy (<10 keV) Helium, Oxygen, Proton, and Electron (HOPE) observations. The dispersed injections of ring current ions observed with the Energetic particle, Composition, and Thermal plasma (ECT) suite at high (>20 keV) energy are better reproduced using a high-resolution convection model. In agreement with Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) observations, RAM-SCB indicates that the large-scale magnetic field is depressed as close as ˜4.5 RE during even a moderate storm. Regions of electromagnetic ion cyclotron instability are predicted on the duskside from ˜6 to ˜9 RE, indicating that previous studies confined to geosynchronous orbit may have underestimated their scattering effect on the energetic particles.

  5. 49 CFR 393.93 - Seats, seat belt assemblies, and seat belt assembly anchorages.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Seats, seat belt assemblies, and seat belt... § 393.93 Seats, seat belt assemblies, and seat belt assembly anchorages. (a) Buses—(1) Buses... the driver's seat and seat belt assembly anchorages that conform to the location and...

  6. 49 CFR 393.93 - Seats, seat belt assemblies, and seat belt assembly anchorages.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 5 2011-10-01 2011-10-01 false Seats, seat belt assemblies, and seat belt... § 393.93 Seats, seat belt assemblies, and seat belt assembly anchorages. (a) Buses—(1) Buses... the driver's seat and seat belt assembly anchorages that conform to the location and...

  7. 30 CFR 75.1731 - Maintenance of belt conveyors and belt conveyor entries.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Maintenance of belt conveyors and belt conveyor....1731 Maintenance of belt conveyors and belt conveyor entries. (a) Damaged rollers, or other damaged belt conveyor components, which pose a fire hazard must be immediately repaired or replaced. All...

  8. 30 CFR 75.1731 - Maintenance of belt conveyors and belt conveyor entries.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Maintenance of belt conveyors and belt conveyor....1731 Maintenance of belt conveyors and belt conveyor entries. (a) Damaged rollers, or other damaged belt conveyor components, which pose a fire hazard must be immediately repaired or replaced. All...

  9. 30 CFR 75.1731 - Maintenance of belt conveyors and belt conveyor entries.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Maintenance of belt conveyors and belt conveyor....1731 Maintenance of belt conveyors and belt conveyor entries. (a) Damaged rollers, or other damaged belt conveyor components, which pose a fire hazard must be immediately repaired or replaced. All...

  10. 30 CFR 75.1731 - Maintenance of belt conveyors and belt conveyor entries.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Maintenance of belt conveyors and belt conveyor....1731 Maintenance of belt conveyors and belt conveyor entries. (a) Damaged rollers, or other damaged belt conveyor components, which pose a fire hazard must be immediately repaired or replaced. All...

  11. 30 CFR 75.1731 - Maintenance of belt conveyors and belt conveyor entries.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Maintenance of belt conveyors and belt conveyor....1731 Maintenance of belt conveyors and belt conveyor entries. (a) Damaged rollers, or other damaged belt conveyor components, which pose a fire hazard must be immediately repaired or replaced. All...

  12. Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models

    SciTech Connect

    Sakaguchi, Kaori; Nagatsuma, Tsutomu; Reeves, Geoffrey D.; Spence, Harlan E.

    2015-12-22

    The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary orbit (GEO) and medium Earth orbit. In order to provide alerts of electron flux enhancements, 16 prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omnidirectional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES 15 spacecraft were used as the predictors. Furthermore, we selected model explanatory parameters from solar wind parameters, the electron log-flux at GEO, and geomagnetic indices. For the innermost region of the outer radiation belt, the electron flux is best predicted by using the Dst index as the sole input parameter. For the central to outermost regions, at L≥4.8 and L ≥5.6, the electron flux is predicted most accurately by including also the solar wind velocity and then the dynamic pressure, respectively. The Dst index is the best overall single parameter for predicting at 3 ≤ L ≤ 6, while for the GEO flux prediction, the KP index is better than Dst. Finally, a test calculation demonstrates that the model successfully predicts the timing and location of the flux maximum as much as 2 days in advance and that the electron flux decreases faster with time at higher L values, both model features consistent with the actually observed behavior.

  13. Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models

    DOE PAGES

    Sakaguchi, Kaori; Nagatsuma, Tsutomu; Reeves, Geoffrey D.; ...

    2015-12-22

    The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary orbit (GEO) and medium Earth orbit. In order to provide alerts of electron flux enhancements, 16 prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omnidirectional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES 15 spacecraftmore » were used as the predictors. Furthermore, we selected model explanatory parameters from solar wind parameters, the electron log-flux at GEO, and geomagnetic indices. For the innermost region of the outer radiation belt, the electron flux is best predicted by using the Dst index as the sole input parameter. For the central to outermost regions, at L≥4.8 and L ≥5.6, the electron flux is predicted most accurately by including also the solar wind velocity and then the dynamic pressure, respectively. The Dst index is the best overall single parameter for predicting at 3 ≤ L ≤ 6, while for the GEO flux prediction, the KP index is better than Dst. Finally, a test calculation demonstrates that the model successfully predicts the timing and location of the flux maximum as much as 2 days in advance and that the electron flux decreases faster with time at higher L values, both model features consistent with the actually observed behavior.« less

  14. Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Kaori; Nagatsuma, Tsutomu; Reeves, Geoffrey D.; Spence, Harlan E.

    2015-12-01

    The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary orbit (GEO) and medium Earth orbit. To provide alerts of electron flux enhancements, 16 prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omnidirectional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES 15 spacecraft were used as the predictors. Model explanatory parameters were selected from solar wind parameters, the electron log-flux at GEO, and geomagnetic indices. For the innermost region of the outer radiation belt, the electron flux is best predicted by using the Dst index as the sole input parameter. For the central to outermost regions, at L ≧ 4.8 and L ≧ 5.6, the electron flux is predicted most accurately by including also the solar wind velocity and then the dynamic pressure, respectively. The Dst index is the best overall single parameter for predicting at 3 ≦ L ≦ 6, while for the GEO flux prediction, the KP index is better than Dst. A test calculation demonstrates that the model successfully predicts the timing and location of the flux maximum as much as 2 days in advance and that the electron flux decreases faster with time at higher L values, both model features consistent with the actually observed behavior.

  15. Recent space shuttle observations of the South Atlantic anomaly and the radiation belt models

    NASA Technical Reports Server (NTRS)

    Konradi, A.; Badhwar, G. D.; Braby, L. A.

    1994-01-01

    Active ingredients consisting of Tissue Equivalent Proportional Counter (TEPC) and a Proton and Heavy Ion Detector (PHIDE) have been carried on a number of Space Shuttle flights. These instruments have allowed us to map out parts of the South Atlantic Particle Anomaly (SAA) and to compare some of it's features with predictions of the AP-8 energetic proton flux models. We have observed that consistent with the generally observed westward drift of the surface features of the terrestial magnetic field of the SAA has moved west by about 6.9 degrees longitude between the epoch year 1970 of the AP-8 solar maximum model and the Space Shuttle observations made twenty years later. However, calculations indicate that except for relatively brief periods following very large magnetic storms the SAA seems to occupy the same position in L-space as in 1970. After the great storm of 24 March 1991 reconfiguration of the inner radiation belt and/or proton injection into the inner belt, a second energetic proton belt was observed to form at approximately equal to 2. As confirmed by a subsequent flight observations, this belt was shown to persist at least for six months. Our measurements also indicate an upward shift in the L location of the primary belt from L = 1.4 to L = 1.5. In addition we confirm through direct real time observations the existence and the approximate magnitude of the East-West effect. If the need exists for improved and updated radiation belt models in the Space Station era, these observations point out the specific features that should be considered and incorporated when this task is undertaken.

  16. Chaos on the conveyor belt.

    PubMed

    Sándor, Bulcsú; Járai-Szabó, Ferenc; Tél, Tamás; Néda, Zoltán

    2013-04-01

    The dynamics of a spring-block train placed on a moving conveyor belt is investigated both by simple experiments and computer simulations. The first block is connected by a spring to an external static point and, due to the dragging effect of the belt, the blocks undergo complex stick-slip dynamics. A qualitative agreement with the experimental results can be achieved only by taking into account the spatial inhomogeneity of the friction force on the belt's surface, modeled as noise. As a function of the velocity of the conveyor belt and the noise strength, the system exhibits complex, self-organized critical, sometimes chaotic, dynamics and phase transition-like behavior. Noise-induced chaos and intermittency is also observed. Simulations suggest that the maximum complexity of the dynamical states is achieved for a relatively small number of blocks (around five).

  17. Conjugate observations of quasiperiodic emissions by the Cluster, Van Allen Probes, and THEMIS spacecraft

    NASA Astrophysics Data System (ADS)

    Němec, F.; Hospodarsky, G.; Pickett, J. S.; Santolík, O.; Kurth, W. S.; Kletzing, C.

    2016-08-01

    We present results of a detailed analysis of two electromagnetic wave events observed in the inner magnetosphere at frequencies of a few kilohertz, which exhibit a quasiperiodic (QP) time modulation of the wave intensity. The events were observed by the Cluster and Van Allen Probes spacecraft and in one event also by the THEMIS E spacecraft. The spacecraft were significantly separated in magnetic local time, demonstrating a huge azimuthal extent of the events. Geomagnetic conditions at the times of the observations were very quiet, and the events occurred inside the plasmasphere. The modulation period observed by the Van Allen Probes and THEMIS E spacecraft (duskside) was in both events about twice larger than the modulation period observed by the Cluster spacecraft (dawnside). Moreover, individual QP elements occur about 15 s earlier on THEMIS E than on Van Allen Probes, which might be related to a finite propagation speed of a modulating ULF wave.

  18. Space Weather data processing and Science Gateway for the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Romeo, G.; Barnes, R. J.; Weiss, M.; Fox, N. J.; Mauk, B.; Potter, M.; Kessel, R.

    2013-12-01

    A near real-time data processing pipeline for the Space Weather broadcast data from the Van Allen Probes is presented. The Van Allen Probes broadcasts a sub-set of the science data in real-time when not downlinking the principal science data. This broadcast is received by several ground stations and relayed to APL in near real time to be ingested into the space weather processing pipeline. This pipeline processes the available level zero space weather data into higher level science data products. These products are made available to the public via the Van Allen Probes Science Gateway website (http://athena.jhuapl.edu). The website acts as pivotal point though which all other instrument SOC's can be accessed. Several other data products (e.g KP/DST indices) and tools (e.g orbit calculator) are made also available to the general public.

  19. An interspecific test of allen's rule: evolutionary implications for endothermic species.

    PubMed

    Nudds, R L; Oswald, S A

    2007-12-01

    Ecogeographical rules provide potential to describe how organisms are morphologically constrained to climatic conditions. Allen's rule (relatively shorter appendages in colder environments) remains largely unsupported and there remains much controversy whether reduced surface area of appendages provides energetic savings sufficient to make this morphological trend truly adaptive. By showing for the first time that Allen's rule holds for closely related endothermic species, we provide persuasive support of the adaptive significance of this trend for multiple species. Our results indicate that reduction of thermoregulatory cost during the coldest part of the breeding season is the most likely mechanism driving Allen's rule for these species. Because for 54% of seabird species examined, rise in seasonal maximum temperature over 100 years will exceed that for minimum temperatures, an evolutionary mismatch will arise between selection for limb length reduction and ability to accommodate heat stress.

  20. Post-workshop models of Jupiter's radiation belts

    NASA Technical Reports Server (NTRS)

    Divine, N.

    1972-01-01

    Models for the charged particle populations of Jupiter's trapped radiation belts were derived at the Jupiter Radiation Belt Workshop on the basis of several assumptions which represented a consensus of opinion. It was possible to improve the models on the basis of work performed after the workshop concluded. These improvements affect the models in two ways. The effects of special relativity on the particle energy and flux dependences in the magnetosphere were included in a derivation based on L-shell diffusion with conservation of the magnetic moment. Quantitative conclusions are available for the limit which ion cyclotron instability places on the proton population. A set of models which incorporates these developments in a way consistent with the original workshop assumptions and conclusions is described.

  1. The distant Kuiper Belt

    NASA Astrophysics Data System (ADS)

    Gladman, B.; Kavelaars, J. J.; Petit, J. M.; Morbidelli, A.; Holman, M.; Loredo, T.

    2000-10-01

    We present results from a series of deep imaging surveys designed to look for very faint objects in the outer solar system. We find roughly 10-20 percent of our detections outside a heliocentric distance of 48 AU, a much larger fraction than all previously published surveys. The implications of this result for the radial structure of the Kuiper Belt will be discussed, as well as how it interacts with various theories regarding the sculpting of the orbital distribution of the trans-Neptunian region. We find a luminosity function with a continuing steep slope down to the limit of our detections at about 26th magnitude, implying that observations are just on the threshold of reaching the level where the TNO size distribution is exptected to `roll over' to a shallower collisional slope. The size distribution in the observed region is expected to hold information about the time scale and physics of planetesimal building in the early outer Solar System. This work has been supported by a Henri Chretien international research grant (AAS), by NASA Origins grants NAG5-8198 and NAG5-9678, by an ACI Jeune award from the French Research Ministry, and an Observatoire de la Côte d'Azur BQR grant.

  2. Proton Therapy

    MedlinePlus

    ... Liver Breast Esophagus Rectum Skull base sarcomas Pediatric brain tumors Head and neck - see the Head and Neck Cancer page Eye ... Intensity-Modulated Radiation Therapy (IMRT) Brain Tumor Treatment Brain Tumors Prostate Cancer Lung Cancer ... related to Proton Therapy Videos related ...

  3. Proton Radiobiology

    PubMed Central

    Tommasino, Francesco; Durante, Marco

    2015-01-01

    In addition to the physical advantages (Bragg peak), the use of charged particles in cancer therapy can be associated with distinct biological effects compared to X-rays. While heavy ions (densely ionizing radiation) are known to have an energy- and charge-dependent increased Relative Biological Effectiveness (RBE), protons should not be very different from sparsely ionizing photons. A slightly increased biological effectiveness is taken into account in proton treatment planning by assuming a fixed RBE of 1.1 for the whole radiation field. However, data emerging from recent studies suggest that, for several end points of clinical relevance, the biological response is differentially modulated by protons compared to photons. In parallel, research in the field of medical physics highlighted how variations in RBE that are currently neglected might actually result in deposition of significant doses in healthy organs. This seems to be relevant in particular for normal tissues in the entrance region and for organs at risk close behind the tumor. All these aspects will be considered and discussed in this review, highlighting how a re-discussion of the role of a variable RBE in proton therapy might be well-timed. PMID:25686476

  4. Experiments in no-impact control of dingoes: comment on Allen et al. 2013.

    PubMed

    Johnson, Christopher N; Crowther, Mathew S; Dickman, Chris R; Letnic, Michael I; Newsome, Thomas M; Nimmo, Dale G; Ritchie, Euan G; Wallach, Arian D

    2014-02-22

    There has been much recent debate in Australia over whether lethal control of dingoes incurs environmental costs, particularly by allowing increase of populations of mesopredators such as red foxes and feral cats. Allen et al. (2013) claim to show in their recent study that suppression of dingo activity by poison baiting does not lead to mesopredator release, because mesopredators are also suppressed by poisoning. We show that this claim is not supported by the data and analysis reported in Allen et al.'s paper.

  5. Replacement of two amino acids of 9R-dioxygenase-allene oxide synthase of Aspergillus niger inverts the chirality of the hydroperoxide and the allene oxide.

    PubMed

    Sooman, Linda; Wennman, Anneli; Hamberg, Mats; Hoffmann, Inga; Oliw, Ernst H

    2016-02-01

    The genome of Aspergillus niger codes for a fusion protein (EHA25900), which can be aligned with ~50% sequence identity to 9S-dioxygenase (DOX)-allene oxide synthase (AOS) of Fusarium oxysporum, homologues of the Fusarium and Colletotrichum complexes and with over 62% sequence identity to homologues of Aspergilli, including (DOX)-9R-AOS of Aspergillus terreus. The aims were to characterize the enzymatic activities of EHA25900 and to identify crucial amino acids for the stereospecificity. Recombinant EHA25900 oxidized 18:2n-6 sequentially to 9R-hydroperoxy-10(E),12(Z)-octadecadienoic acid (9R-HPODE) and to a 9R(10)-allene oxide. 9S- and 9R-DOX-AOS catalyze abstraction of the pro-R hydrogen at C-11, but the direction of oxygen insertion differs. A comparison between twelve 9-DOX domains of 9S- and 9R-DOX-AOS revealed conserved amino acid differences, which could contribute to the chirality of products. The Gly616Ile replacement of 9R-DOX-AOS (A. niger) increased the biosynthesis of 9S-HPODE and the 9S(10)-allene oxide, whereas the Phe627Leu replacement led to biosynthesis of 9S-HPODE and the 9S(10)-allene oxide as main products. The double mutant (Gly616Ile, Phe627Leu) formed over 90% of the 9S stereoisomer of HPODE. 9S-HPODE was formed by antarafacial hydrogen abstraction and oxygen insertion, i.e., the original H-abstraction was retained but the product chirality was altered. We conclude that 9R-DOX-AOS can be altered to 9S-DOX-AOS by replacement of two amino acids (Gly616Ile, Phe627Leu) in the DOX domain.

  6. Belt conveyors for bulk materials. 6th ed.

    SciTech Connect

    2007-07-01

    The 16 chapters are entitled: Belt conveyor general applications economics; Design considerations; Characteristics and conveyability of bulk materials; Capacities, belt widths and speeds; Belt conveyor idlers; Belt tension and power engineering; Belt selection; Pulleys and shafts; Curves; Steep angle conveying; Belt cleaners and accessories; Transfer points; Conveyor motor drives and controls; Operation, maintenance and safety; Belt takeups; and Emerging technologies. 6 apps.

  7. A Critique of Mark D. Allen's "The Preservation of Verb Subcategory Knowledge in a Spoken Language Comprehension Deficit"

    ERIC Educational Resources Information Center

    Kemmerer, David

    2008-01-01

    Allen [Allen, M. (2005). "The preservation of verb subcategory knowledge in a spoken language comprehension deficit." "Brain and Language, 95", 255-264.] reports a single patient, WBN, who, during spoken language comprehension, is still able to access some of the syntactic properties of verbs despite being unable to access some of their semantic…

  8. Northern Belt of Jupiter

    NASA Technical Reports Server (NTRS)

    2000-01-01

    [figure removed for brevity, see original site]

    A four-panel frame shows a section of Jupiter's north equatorial belt viewed by NASA's Cassini spacecraft at four different wavelengths, and a separate reference frame shows the location of the belt on the planet.

    A fascinating aspect of the images in the four-panel frame is the small bright spot in the center of each. The images come from different layers of the atmosphere, so the spot appears to be a storm penetrating upward through several layers. This may in fact be a 'monster' thunderstorm, penetrating all the way into the stratosphere, as do some summer thunderstorms in the midwestern United States. These images were taken on Nov. 27, 2000, at a resolution of 192 kilometers (119 miles) per pixel. They have been contrast-enhanced to highlight features in the atmosphere.

    The top panel of the four-panel frame is an image taken in a near-infrared wavelength at which the gases in Jupiter's atmosphere are relatively non-absorbing. Sunlight can penetrate deeply into the atmosphere at this wavelength and be reflected back out, providing a view of an underlying region of the atmosphere, the lower troposphere.

    The second panel was taken in the blue portion of wavelengths detected by the human eye. At these wavelengths, gases in the atmosphere scatter a modest amount of sunlight, so the clouds we see tend to be at somewhat higher altitudes than in the top panel.

    The third panel shows near-infrared reflected sunlight at a wavelength where the gas methane, an important constituent of Jupiter's atmosphere, absorbs strongly. Dark places are regions without high-level clouds and consequently large amounts of methane accessible to sunlight. Bright regions are locations with high clouds in the upper troposphere shielding the methane below.

    The bottom panel was taken in the ultraviolet. At these very short wavelengths, the clear atmosphere scatters sunlight, and hazes in the stratosphere, above the troposphere

  9. Generation of Nonlinear Electric Field Bursts in the Outer Radiation Belt through Electrons Trapping by Oblique Whistler Waves

    NASA Astrophysics Data System (ADS)

    Agapitov, Oleksiy; Drake, James; Mozer, Forrest

    2016-04-01

    Huge numbers of different nonlinear structures (double layers, electron holes, non-linear whistlers, etc. referred to as Time Domain Structures - TDS) have been observed by the electric field experiment on board the Van Allen Probes. A large part of the observed non-linear structures are associated with whistler waves and some of them can be directly driven by whistlers. The parameters favorable for the generation of TDS were studied experimentally as well as making use of 2-D particle-in-cell (PIC) simulations for the system with inhomogeneous magnetic field. It is shown that an outward propagating front of whistlers and hot electrons amplifies oblique whistlers which collapse into regions of intense parallel electric field with properties consistent with recent observations of TDS from the Van Allen Probe satellites. Oblique whistlers seed the parallel electric fields that are driven by the beams. The resulting parallel electric fields trap and heat the precipitating electrons. These electrons drive spikes of intense parallel electric field with characteristics similar to the TDSs seen in the VAP data. The decoupling of the whistler wave and the nonlinear electrostatic component is shown in PIC simulation in the inhomogeneous magnetic field system. These effects are observed by the Van Allen Probes in the radiation belts. The precipitating hot electrons propagate away from the source region in intense bunches rather than as a smooth flux.

  10. Generation of Nonlinear Electric Field Bursts in the Outer Radiation Belt through Electrons Trapping by Oblique Whistler Waves

    NASA Astrophysics Data System (ADS)

    Agapitov, O. V.; Drake, J. F.; Mozer, F.

    2015-12-01

    Huge numbers of different nonlinear structures (double layers, electron holes, non-linear whistlers, etc. referred to as Time Domain Structures - TDS) have been observed by the electric field experiment on board the Van Allen Probes. A large part of the observed non-linear structures are associated with whistler waves and some of them can be directly driven by whistlers. The parameters favorable for the generation of TDS were studied experimentally as well as making use of 2-D particle-in-cell (PIC) simulations for the system with inhomogeneous magnetic field. It is shown that an outward propagating front of whistlers and hot electrons amplifies oblique whistlers which collapse into regions of intense parallel electric field with properties consistent with recent observations of TDS from the Van Allen Probe satellites. Oblique whistlers seed the parallel electric fields that are driven by the beams. The resulting parallel electric fields trap and heat the precipitating electrons. These electrons drive spikes of intense parallel electric field with characteristics similar to the TDSs seen in the VAP data. The decoupling of the whistler wave and the nonlinear electrostatic component is shown in PIC simulation in the inhomogeneous magnetic field system. These effects are observed by the Van Allen Probes in the radiation belts. The precipitating hot electrons propagate away from the source region in intense bunches rather than as a smooth flux.

  11. The Living with a Star Radiation Belt Storm Probes Mission and Related Missions of Opportunity

    NASA Technical Reports Server (NTRS)

    Sibeck, David G.; Mauk, Barry H.; Grebowsky, Joseph M.; Fox, Nicola J.

    2006-01-01

    This presentation provides an overview of the Living With a Star (LWS) Radiation Belt Storm Probes (RBSP) mission in the context of the broader Geospace program. Missions to Geospace offer an opportunity to observe in situ the fundamental processes that operate throughout the solar system and in particular those that generate hazardous space weather effects in the vicinity of Earth. The recently selected investigations on NASA's LWS program's RBSP will provide the measurements needed to characterize and quantify the processes that supply and remove energetic particles from the Earth's Van Allen radiation belts. Instruments on the RBSP spacecraft will observe charged particles that comprise the Earth's radiation belts over the full energy range from 1 eV to more than 10 MeV (including composition), the plasma waves which energize them, the electric fields which transport them, and the magnetic fields which guide their motion. The two-point measurements by the RBSP spacecraft will enable researchers to discriminate between spatial and temporal effects, and therefore between the various proposed mechanisms for particle acceleration and loss. The measurements taken by the RBSP spacecraft will be used in data modeling projects in order to improve the understanding of these fundamental processes and allow better predictions to be made. NASA's LWS program has also recently selected three teams to study concepts for Missions of Opportunity that will augment the RBSP program, by (1) providing an instrument for a Canadian spacecraft in the Earth's radiation belts, (2) quantifying the flux of particles precipitating into the Earth's atmosphere from the Earth's radiation belts, and (3) remotely sensing both spatial and temporal variations in the Earth's ionosphere and thermosphere.

  12. Implementation of Localized Ensemble Assimilation for a Three-Dimensional Radiation Belt Model (Invited)

    NASA Astrophysics Data System (ADS)

    Godinez, H. C.; Chen, Y.; Kellerman, A. C.; Subbotin, D.; Shprits, Y.

    2013-12-01

    Earth's outer radiation belt is very dynamic and energetic electrons therein undergo constant changes due to acceleration, loss, and trans- port processes. In this work we improve the accuracy of simulated electron phase space density (PSD) of the Versatile Electron Radiation Belt (VERB) code, a three-dimensional radiation belt model, by implementing the localized ensemble transform Kalman filter (LETKF) assimilation method. Assimilation methods based on Kalman filtering have been successfully applied to one-dimensional radial diffusion radiation belt models, where it has been shown to greatly improve the model estimation of electron phase space density (PSD). This work expands upon previous research by implementing the LETKF method to assimilate observed electron density into VERB, a three-dimensional radiation belt model. In particular, the LETKF will perform the assimilation locally, where the size of the local region is defined by the diffusion of electrons in the model. This will enable the optimal assimilation of data throughout the model consistently with the flow of electrons. Two sets of assimilation experiments are presented. The first is an identical-twin experiment, where artificial data is generated from the same model, with the purpose of verifying the assimilation method. In the second set of experiments, real PSD observational data from missions such as CRRES and/or the Van Allen Probes are assimilated into VERB. The results show that data assimilation significantly improves the accuracy of the VERB model by efficiently including the available observations at the appropriate pitch angles, energy levels, and L-shell regions throughout the model.

  13. Investigating the source of near-relativistic and relativistic electrons in Earth's inner radiation belt

    DOE PAGES

    Turner, Drew Lawson; O'Brien, T. P.; Fennell, J. F.; ...

    2017-01-30

    Using observations from NASA's Van Allen Probes, we study the role of sudden particle enhancements at low L shells (SPELLS) as a source of inner radiation belt electrons. SPELLS events are characterized by electron intensity enhancements of approximately an order of magnitude or more in less than 1 day at L < 3. During quiet and average geomagnetic conditions, the phase space density radial distributions for fixed first and second adiabatic invariants are peaked at 2 < L < 3 for electrons ranging in energy from ~50 keV to ~1 MeV, indicating that slow inward radial diffusion is not themore » dominant source of inner belt electrons under quiet/average conditions. During SPELLS events, the evolution of electron distributions reveals an enhancement of phase space density that can exceed 3 orders of magnitude in the slot region and continues into the inner radiation belt, which is evidence that these events are an important—and potentially dominant—source of inner belt electrons. Electron fluxes from September 2012 through February 2016 reveal that SPELLS occur frequently (~2.5/month at 200 keV), but the number of observed events decreases exponentially with increasing electron energy for ≥100 keV. After SPELLS events, the slot region reforms due to slow energy-dependent decay over several day time scales, consistent with losses due to interactions with plasmaspheric hiss. Altogether, these results indicate that the peaked phase space density distributions in the inner electron radiation belt result from an “on/off,” geomagnetic-activity-dependent source from higher radial distances.« less

  14. Investigating the source of near-relativistic and relativistic electrons in Earth's inner radiation belt

    NASA Astrophysics Data System (ADS)

    Turner, D. L.; O'Brien, T. P.; Fennell, J. F.; Claudepierre, S. G.; Blake, J. B.; Jaynes, A. N.; Baker, D. N.; Kanekal, S.; Gkioulidou, M.; Henderson, M. G.; Reeves, G. D.

    2017-01-01

    Using observations from NASA's Van Allen Probes, we study the role of sudden particle enhancements at low L shells (SPELLS) as a source of inner radiation belt electrons. SPELLS events are characterized by electron intensity enhancements of approximately an order of magnitude or more in less than 1 day at L < 3. During quiet and average geomagnetic conditions, the phase space density radial distributions for fixed first and second adiabatic invariants are peaked at 2 < L < 3 for electrons ranging in energy from 50 keV to 1 MeV, indicating that slow inward radial diffusion is not the dominant source of inner belt electrons under quiet/average conditions. During SPELLS events, the evolution of electron distributions reveals an enhancement of phase space density that can exceed 3 orders of magnitude in the slot region and continues into the inner radiation belt, which is evidence that these events are an important - and potentially dominant - source of inner belt electrons. Electron fluxes from September 2012 through February 2016 reveal that SPELLS occur frequently ( 2.5/month at 200 keV), but the number of observed events decreases exponentially with increasing electron energy for ≥100 keV. After SPELLS events, the slot region reforms due to slow energy-dependent decay over several day time scales, consistent with losses due to interactions with plasmaspheric hiss. Combined, these results indicate that the peaked phase space density distributions in the inner electron radiation belt result from an "on/off," geomagnetic-activity-dependent source from higher radial distances.

  15. A mantle conveyor belt beneath the Tethyan collisional belt

    NASA Astrophysics Data System (ADS)

    Becker, T. W.; Faccenna, C.

    2011-12-01

    Collisional belts are generated by the arrival of continental lithosphere into a subduction zone, leading to stacking of crustal slices during indentation. The Tethyan suture from the Bitlis to the Himalayas is a prime example where the Arabian and Indian plates collided with Eurasia during the Cenozoic, generating the highest mountain belts on Earth (Argand, 1924). While the kinematics of this process are well established, its dynamics are more uncertain. India and Arabia intriguingly keep advancing in spite of large collisional resisting forces. We perform global mantle circulation computations to test the role of deep mantle flow as a driving force for the kinematics of the Tethyan collisional belt, evaluating different boundary conditions and mantle density distributions as inferred from seismic tomography or slab models. Our results show that mantle drag exerted on the base of the lithosphere by a large-scale upwelling is likely the main cause for the ongoing indentation of the Indian and Arabian plates into Eurasia.

  16. Proton maser

    NASA Astrophysics Data System (ADS)

    Ensley, D. L.

    1988-01-01

    New calculations are reported which confirm the ability of an a priori random, initial-phase proton beam to drive a simple, single-stage microwave cavity maser or transit-time oscillator (TTO) to saturation conversion efficiencies of about 11 percent. The required initial TE(011) mode field can be provided from beam ramp-up bandwidth of excitation to a low level from an external source. A saturation field of 45 tesla and output power of 0.2 TW are calculated using an electron insulation field of 10 tesla and a 3 MeV, 400 Ka/sq cm beam. Results are compared to those for an electron beam of the same energy and geometry, and it is shown that proton beams potentially can provide a three order of magnitude increase in overall microwave power production density over that obtainable from electron beam TTOs.

  17. Regioselective Allene Hydrosilylation Catalyzed by NHC Complexes of Nickel and Palladium

    PubMed Central

    Miller, Zachary D.; Li, Wei; Belderrain, Tomás R.; Montgomery, John

    2013-01-01

    Regioselective methods for allene hydrosilylation have been developed, with regioselectivity being governed primarily by choice of metal. Alkenylsilanes are produced via nickel catalysis with larger N-heterocyclic carbene ligands, and allylsilanes are produced via palladium catalysis with smaller N-heterocyclic carbene ligands. These complementary methods allow either regioisomeric product to be obtained with exceptional regiocontrol. PMID:24079389

  18. Phosphorus-Containing Bis-allenes: Synthesis and Heterocyclization Reactions Mediated by Iodine or Copper Dibromide.

    PubMed

    Essid, I; Laborde, C; Legros, F; Sevrain, N; Touil, S; Rolland, M; Ayad, T; Volle, J-N; Pirat, J-L; Virieux, D

    2017-03-30

    Bisphosphorylallenes were easily obtained in multigram scale from the Wittig-type rearrangement of bispropargyl alcohols. Unlike other conjugated bis-allenes, these reagents underwent a double cyclization mediated by iodine or copper dibromide leading to the formation of bis-1,2-oxaphospholenes.

  19. No Radio Flaring Detected from Cygnus X-3 at 3 GHz by Allen Telescope Array

    NASA Astrophysics Data System (ADS)

    Williams, P. K. G.; Bower, G. C.; Tomsick, J. A.; Bodaghee, A.; Corbet, R. H. D.

    2011-01-01

    Following the announcement of a 98 GHz flare from the microquasar Cygnus X-3 (ATel #3130), we observed it with the Allen Telescope Array (Welch et al., 2009 Proc. IEEE 97 1438 for 2.5 hours beginning at 2011 January 28.848 UT (MJD 55589.848), about 4.0 hours after the 98 GHz observations concluded.

  20. Astronauts Gardner and Allen on the RMS after recapture of Westar VI

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Dale A. Gardner, left, holds a 'For Sale' sign, making light reference to the status of the recaptured communications satellite. Astronaut Joseph P. ALlen IV stands on the mobile foot restraint (MFR), which in tandem with the remote manipulator system (RMS) arm served as a cherry-picker for capture efforts.

  1. Astronauts Gardner and Allen during loading of Palapa B-2 in payload bay

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Joseph P. Allen IV, left, tethered to the orbiting Discovery, holds onto the Palapa B-2 satellite with his right hand while Astronaut Dale A. Gardner returns the used 'stinger' device to its stowage area. The payload bay is open, showing the area where the satellite will be stowed for the return to Earth.

  2. All Together Now: Valerie Allen--U.S. Department of Energy

    ERIC Educational Resources Information Center

    Library Journal, 2005

    2005-01-01

    When Valerie Allen decided she did not want to be a Montessori teacher any longer, she began work on her MLIS. Immediately she learned concepts she could apply to her new job as information specialist for the Department of Energy's (DOE) Office of Scientific and Technical Information (OSTI) at Oak Ridge National Laboratory, TN. While the LIS…

  3. Free Pulp Transfer for Fingertip Reconstruction—The Algorithm for Complicated Allen Fingertip Defect

    PubMed Central

    Spyropoulou, Georgia-Alexandra; Shih, Hsiang-Shun

    2015-01-01

    Abstract Background: We present a review of all the cases of free toe pulp transfer and an algorithm for application of free pulp transfer in complicated Allen fingertip defect. Methods: Seventeen patients underwent free toe pulp transfer for fingertip reconstruction by the senior author. Twelve cases were Allen type II with oblique pulp defect, 4 were Allen type III, and 1 patient had 2 fingertip injuries classified both as type IV. According to the algorithm presented, for the type III defects where the germinal matrix is still preserved, we use free pulp transfer and nail bed graft to preserve the nail growth instead of toe to hand transfer. For the type IV injuries with multiple defects, a combination of web flap from both big toe and second toe is possible for 1-stage reconstruction. Results: All pulp flaps survived completely. Static 2-point discrimination ranged from 6 to 15 mm (mean: 10.5 mm). No patient presented dysesthesia, hyperesthesia, pain at rest, or cold intolerance. The donor site did not present any nuisances apart from partial skin graft loss in 3 cases. Conclusions: We tried to classify and modify the defects’ reconstruction according to Allen classification. Free toe pulp transfer is a “like with like” reconstruction that provides sensate, glabrous skin with good color and texture match for fingertip trauma, and minimal donor site morbidity compared with traditional toe to hand transfer. PMID:26894009

  4. Astronauts Joseph Allen rides cherry picker over stowage area/work station

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Joseph P. Allen rides a cherry picker over to a stowage area/work station to wrap up extravehicular activity (EVA) duties above Earth. The cherry picker is a union of the mobile foot restraint and the remote manipulator system (RMS), controlled from inside Discovery's cabin. The Westar VI/PAM-D satellite is pictured secured in Discovery's cargo bay.

  5. Trends in PVC conveyor belting

    SciTech Connect

    Hopwood, J.E.

    1984-03-01

    The development of mechanical systems of extraction at the coal face necessitated the introduction of efficient methods of mineral transportation in deep-mining operations. The most popular system is the belt conveyor. Originally PVC was being evaluated as a rubber substitute, as in its liquid form it appeared to offer an easier route to fabric coating and impregnation for conveyor belt applications. However, it was not until 1950, when over 200 miners lost their lives due to an underground fire being spread by combustible rubber conveyor belts, that the full significance of the properties of PVC were appreciated. Following this tragedy, an intensive development program to produce a substitute for rubber was initiated. It had to have similar operational characteristics as rubber while incorporating the safety features of resistance to flame propagation and build-up of static electrical charges. It became evident that PVC could be compounded to realize these requirements and belting manufacturers immediately started to produce a new generation of belts based on the previouly proven mechanical characteristics of multiply fabrics, but substituting PVC for the rubber content. The advantages of PVC are discussed.

  6. On the threshold energization of radiation belt electrons by double layers.

    NASA Astrophysics Data System (ADS)

    Dimmock, A. P.; Osmane, A.; Pulkkinen, T. I.

    2014-12-01

    Recent in situ electric field measurements by the Van Allen Probes in the radiation belts have revealed the existence and ubiquitous presence of double layers [Mozer et al. Phys. Rev. Lett., 2013]. Encounters with double layers during 1 minute burst mode intervals were both common and indicative of large cumulative potential drops. With electric fields averaging 20 mV/m, and sometimes reaching as high as 100 mV/m, observed double layers have been suggested as possible accelerators of radiation belt electrons and generators of a seed population of 100 keV. Using a Hamiltonian approach we quantify the energization threshold of electrons interacting with radiation belts' double layers analytically and numerically. We find that double layers with electric field amplitude δE ranging between 10-100 mV/m and spatial scales of the order of few Debye lengths are very efficient in energizing electrons with initial velocities v ≤ vthermal≈3000 km/s to 1 keV levels, but are unable to energize electrons with energies E ≥ 10 keV. Our results therefore indicate that the localized electric field associated with the double layers are unlikely to generate a seed population of 100 keV necessary for a plethora of relativistic acceleration mechanisms and additional transport to higher energetic levels.

  7. Solar wind conditions leading to efficient radiation belt electron acceleration: A superposed epoch analysis

    DOE PAGES

    Li, W.; Thorne, R. M.; Bortnik, J.; ...

    2015-09-07

    In this study by determining preferential solar wind conditions leading to efficient radiation belt electron acceleration is crucial for predicting radiation belt electron dynamics. Using Van Allen Probes electron observations (>1 MeV) from 2012 to 2015, we identify a number of efficient and inefficient acceleration events separately to perform a superposed epoch analysis of the corresponding solar wind parameters and geomagnetic indices. By directly comparing efficient and inefficient acceleration events, we clearly show that prolonged southward Bz, high solar wind speed, and low dynamic pressure are critical for electron acceleration to >1 MeV energies in the heart of the outermore » radiation belt. We also evaluate chorus wave evolution using the superposed epoch analysis for the identified efficient and inefficient acceleration events and find that chorus wave intensity is much stronger and lasts longer during efficient electron acceleration events, supporting the scenario that chorus waves play a key role in MeV electron acceleration.« less

  8. On the Connection Between Microbursts and Nonlinear Electronic Structures in Planetary Radiation Belts

    NASA Technical Reports Server (NTRS)

    Osmane, Adnane; Wilson, Lynn B., III; Blum, Lauren; Pulkkinen, Tuija I.

    2016-01-01

    Using a dynamical-system approach, we have investigated the efficiency of large-amplitude whistler waves for causing microburst precipitation in planetary radiation belts by modeling the microburst energy and particle fluxes produced as a result of nonlinear wave-particle interactions. We show that wave parameters, consistent with large amplitude oblique whistlers, can commonly generate microbursts of electrons with hundreds of keV-energies as a result of Landau trapping. Relativistic microbursts (greater than 1 MeV) can also be generated by a similar mechanism, but require waves with large propagation angles Theta (sub k)B greater than 50 degrees and phase-speeds v(sub phi) greater than or equal to c/9. Using our result for precipitating density and energy fluxes, we argue that holes in the distribution function of electrons near the magnetic mirror point can result in the generation of double layers and electron solitary holes consistent in scales (of the order of Debye lengths) to nonlinear structures observed in the radiation belts by the Van Allen Probes. Our results indicate a relationship between nonlinear electrostatic and electromagnetic structures in the dynamics of planetary radiation belts and their role in the cyclical production of energetic electrons (E greater than or equal to 100 keV) on kinetic timescales, which is much faster than previously inferred.

  9. Energization of outer radiation belt electrons during storm recovery phase

    NASA Astrophysics Data System (ADS)

    Shah, Asif; Waters, C. L.; Sciffer, M. D.; Menk, F. W.

    2016-11-01

    We use test particle simulations incorporating an MHD model of ULF wave propagation in the magnetosphere with realistic ionosphere boundary conditions to study electron energization in the dayside outer Van Allen radiation belt, referenced to in situ particle and wave observations. On 7 January 2011 the THEMIS spacecraft detected 3 and 4-5 mHz waves simultaneous with flux enhancement of >10 keV electrons during the early recovery phase of a moderate geomagnetic storm. We find that internal energization of equatorially mirroring electrons via nonresonant ULF wave-particle interactions can explain these observations. The wave poloidal components cause radial drift of electrons, increasing (decreasing) their kinetic energy as they move inward (outward). Electrons with initial kinetic energies of a few keV can be energized to double these values within an hour by interaction with the 3 mHz waves. The energization rate is somewhat less for the 4-5 mHz waves. An increase in the ionospheric conductance decreases the power of the fast mode wave, reducing radial drift velocities and hence decreasing the rate of energization. The fast mode poloidal field varies with radial distance and longitude, and this also affects energization. Electrons which drift outward encounter a region where the toroidal field due to the field line resonance becomes dominant and produces strong azimuthal drift. These electrons become trapped in an L-shell range just outward of the resonance region and are not energized.

  10. Mercury's plasma belt: hybrid simulations results compared to in-situ measurements

    NASA Astrophysics Data System (ADS)

    Hercik, D.; Travnicek, P. M.; Schriver, D.; Hellinger, P.

    2012-12-01

    The presence of plasma belt and trapped particles region in the Mercury's inner magnetosphere has been questionable due to small dimensions of the magnetosphere of Mercury compared to Earth, where these regions are formed. Numerical simulations of the solar wind interaction with Mercury's magnetic field suggested that such a structure could be found also in the vicinity of Mercury. These results has been recently confirmed also by MESSENGER observations. Here we present more detailed analysis of the plasma belt structure and quasi-trapped particle population characteristics and behaviour under different orientations of the interplanetary magnetic field.The plasma belt region is constantly supplied with solar wind protons via magnetospheric flanks and tail current sheet region. Protons inside the plasma belt region are quasi-trapped in the magnetic field of Mercury and perform westward drift along the planet. This region is well separated by a magnetic shell and has higher average temperatures and lower bulk proton current densities than surrounding area. On the day side the population exhibits loss cone distribution function matching the theoretical loss cone angle. Simulations results are also compared to in-situ measurements acquired by MESSENGER MAG and FIPS instruments.

  11. Apparatus for forming drive belts

    NASA Technical Reports Server (NTRS)

    Topits, A., Jr. (Inventor)

    1974-01-01

    An apparatus for manufacturing belts, such as seamless belts, is provided, the apparatus has relatively movable rollers that are mounted in an oven. A belt blank, for example, of a thin polyester film, is rotated on the rollers as heat is applied. Four rollers, each mounted on a separate roller assembly, are movable along appropriate tracks while a fifth centrally located roller is stationary. A pair of dc motors are operatively connected to a speed reduction gear assembly to provide a pair of rotating drive shafts that extend into the oven. One rotating shaft drives all of the rollers through a rotational gear assembly while the other drive shaft is capable of positioning the movable rollers through respective rotating threaded shafts. Control devices are provided for controlling the motors while measuring devices are operatively connected to the positional drive shaft to indicate the position of the rollers.

  12. Dynamics of Radiation Belt Particles

    NASA Astrophysics Data System (ADS)

    Ukhorskiy, A. Y.; Sitnov, M. I.

    2013-11-01

    This paper reviews basic concepts of particle dynamics underlying theoretical aspect of radiation belt modeling and data analysis. We outline the theory of adiabatic invariants of quasiperiodic Hamiltonian systems and derive the invariants of particle motion trapped in the radiation belts. We discuss how the nonlinearity of resonant interaction of particles with small-amplitude plasma waves, ubiquitous across the inner magnetosphere, can make particle motion stochastic. Long-term evolution of a stochastic system can be described by the Fokker-Plank (diffusion) equation. We derive the kinetic equation of particle diffusion in the invariant space and discuss its limitations and associated challenges which need to be addressed in forthcoming radiation belt models and data analysis.

  13. On the Cross-Energy Cross-Pitch-Angle Coherence of Electrons in the Outer Radiation Belt

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Reeves, G. D.; Tu, W.; Cunningham, G.; Henderson, M. G.; Kletzing, C.; Redmon, R. J.

    2014-12-01

    Relativistic electrons, mainly trapped in the Earth's outer radiation belt, present a highly hazardous radiation environment for electronic hardware on board satellites and spacecraft. Thus developing a predictive capability for MeV electron levels as well as understanding the physics have been deemed critical for both space research and industry communities. In this work, we first demonstrate that a high cross-energy cross-pitch-angle coherence exists between the trapped ~MeV electrons and precipitating ~100s KeV electrons—observed respectively by Van Allen Probes and NOAA POES satellites in different orbits—by conducting a correlation survey on measurements from both high- and low-altitudes. Then, based upon the results, we further test the possibility of using a linear prediction filter model, driven by POES observations from low-Earth-orbits, to predict the energization of MeV electrons after geomagnetic storms, as well as the evolving distributions of MeV electrons in real time. Finally, to account for this high coherence, we provide our hypothesis based upon theoretical calculations and numerical simulations for individual events using diffusion codes with realistic particle and wave inputs from missions including Van Allen Probes. Results from this study unveil new knowledge on radiation belt dynamics, add new science significance to a long existing space infrastructure, and provide practical and useful tools to the whole space community.

  14. Dawn-dusk asymmetry and adiabatic dynamic of the radiation belt electrons during magnetic storm

    NASA Astrophysics Data System (ADS)

    Lazutin, Leonid L.

    2016-09-01

    The changes of the latitudinal profiles of outer belt energetic electrons during magnetic storms are mostly explained by the precipitation into the loss cone caused by VLF and EMIC waves or by the scattering into the magnetopause. In present work, energetic electron dynamics during magnetic storm of August 29-30, 2004 we attributed at most to the adiabatic transformation of the magnetic drift trajectories and Dst effect. This conclusion was based on the analysis of dawn-dusk asymmetry of the electron latitudinal profiles measured by low altitude polar orbiter SERVIS-1 and on the coincidence of pre-storm and after-storm profiles of radiation belt electrons and protons.

  15. Theory for charge states of energetic oxygen ions in the earth's radiation belts

    NASA Technical Reports Server (NTRS)

    Spjeldvik, W. N.; Fritz, T. A.

    1978-01-01

    Fluxes of geomagnetically trapped energetic oxygen ions have been studied in detail. Ion distributions in radial locations below the geostationary orbit, energy spectra between 1 keV and 100 MeV, and the distribution over charge states have been computed for equatorially mirroring ions. Both ionospheric and solar wind oxygen ion sources have been considered, and it is found that the charge state distributions in the interior of the radiation belts are largely independent of the charge state characteristics of the sources. In the MeV range, oxygen ions prove to be a more sensitive probe for radiation belt dynamics than helium ions and protons.

  16. 14 CFR 31.63 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS: MANNED FREE BALLOONS Design Construction § 31.63 Safety belts. (a) There must be a safety belt... requirements of Subpart C of this part. (b) This section does not apply to balloons that incorporate a...

  17. 14 CFR 31.63 - Safety belts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS: MANNED FREE BALLOONS Design Construction § 31.63 Safety belts. (a) There must be a safety belt... requirements of subpart C of this part. (b) This section does not apply to balloons that incorporate a...

  18. 14 CFR 31.63 - Safety belts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS: MANNED FREE BALLOONS Design Construction § 31.63 Safety belts. (a) There must be a safety belt... requirements of subpart C of this part. (b) This section does not apply to balloons that incorporate a...

  19. 14 CFR 31.63 - Safety belts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... STANDARDS: MANNED FREE BALLOONS Design Construction § 31.63 Safety belts. (a) There must be a safety belt... requirements of subpart C of this part. (b) This section does not apply to balloons that incorporate a...

  20. Proton scaling

    SciTech Connect

    Canavan, Gregory H

    2009-01-01

    This note presents analytic estimates of the performance of proton beams in remote surveillance for nuclear materials. The analysis partitions the analysis into the eight steps used by a companion note: (1) Air scattering, (2) Neutron production in the ship and cargo, (3) Target detection probability, (4) Signal produced by target, (5) Attenuation of signal by ship and cargo, (6) Attenuation of signal by air, (7) Geometric dilution, and (8) Detector Efficiency. The above analyses indicate that the dominant air scattering and loss mechanisms for particle remote sensing are calculable with reliable and accepted tools. They make it clear that the conversion of proton beams into neutron sources rapidly goes to completion in all but thinnest targets, which means that proton interrogation is for all purposes executed by neutrons. Diffusion models and limiting approximations to them are simple and credible - apart from uncertainty over the cross sections to be used in them - and uncertainty over the structure of the vessels investigated. Multiplication is essentially unknown, in part because it depends on the details of the target and its shielding, which are unlikely to be known in advance. Attenuation of neutron fluxes on the way out are more complicated due to geometry, the spectrum of fission neutrons, and the details of their slowing down during egress. The attenuation by air is large but less uncertain. Detectors and technology are better known. The overall convolution of these effects lead to large but arguably tolerable levels of attenuation of input beams and output signals. That is particularly the case for small, mobile sensors, which can more than compensate for size with proximity to operate reliably while remaining below flux limits. Overall, the estimates used here appear to be of adequate accuracy for decisions. That assessment is strengthened by their agreement with companion calculations.

  1. Enantioselective Synthesis of 5,7-Bicyclic Ring Systems from Axially Chiral Allenes Using a Rh(I)-Catalyzed Cyclocarbonylation Reaction

    PubMed Central

    Grillet, Francois; Brummond, Kay M.

    2013-01-01

    A transfer of chirality in an intramolecular Rh(I)-catalyzed allenic Pauson-Khand reaction (APKR) to access tetrahydroazulenones, tetrahydrocyclopenta[c]azepinones and dihydrocyclopenta[c]oxepinones enantioselectively (22 – 99% ee) is described. The substitution pattern of the allene affected the transfer of chiral information. Complete transfer of chirality was obtained for all trisubstituted allenes, but loss of chiral information was observed for disubstituted allenes. This work constitutes the first demonstration of a transfer of chiral information from an allene to the 5-position of a cyclopentenone using a cyclocarbonylation reaction. The absolute configuration of the corresponding cyclocarbonylation product was also established, something that is rarely done. PMID:23485149

  2. 46 CFR 169.723 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Safety belts. 169.723 Section 169.723 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.723 Safety belts. Each vessel must carry a harness type safety belt conforming to Offshore Racing Council (ORC) standards for each person on watch...

  3. 36 CFR 4.15 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Safety belts. 4.15 Section 4... TRAFFIC SAFETY § 4.15 Safety belts. (a) Each operator and passenger occupying any seating position of a motor vehicle in a park area will have the safety belt or child restraint system properly fastened...

  4. 46 CFR 169.723 - Safety belts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Safety belts. 169.723 Section 169.723 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.723 Safety belts. Each vessel must carry a harness type safety belt conforming to Offshore Racing Council (ORC) standards for each person on watch...

  5. 36 CFR 4.15 - Safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Safety belts. 4.15 Section 4... TRAFFIC SAFETY § 4.15 Safety belts. (a) Each operator and passenger occupying any seating position of a motor vehicle in a park area will have the safety belt or child restraint system properly fastened...

  6. 36 CFR 4.15 - Safety belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Safety belts. 4.15 Section 4... TRAFFIC SAFETY § 4.15 Safety belts. (a) Each operator and passenger occupying any seating position of a motor vehicle in a park area will have the safety belt or child restraint system properly fastened...

  7. 46 CFR 169.723 - Safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Safety belts. 169.723 Section 169.723 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.723 Safety belts. Each vessel must carry a harness type safety belt conforming to Offshore Racing Council (ORC) standards for each person on watch...

  8. 46 CFR 169.723 - Safety belts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Safety belts. 169.723 Section 169.723 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.723 Safety belts. Each vessel must carry a harness type safety belt conforming to Offshore Racing Council (ORC) standards for each person on watch...

  9. 46 CFR 169.723 - Safety belts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Safety belts. 169.723 Section 169.723 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.723 Safety belts. Each vessel must carry a harness type safety belt conforming to Offshore Racing Council (ORC) standards for each person on watch...

  10. 36 CFR 4.15 - Safety belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Safety belts. 4.15 Section 4... TRAFFIC SAFETY § 4.15 Safety belts. (a) Each operator and passenger occupying any seating position of a motor vehicle in a park area will have the safety belt or child restraint system properly fastened...

  11. 36 CFR 4.15 - Safety belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Safety belts. 4.15 Section 4... TRAFFIC SAFETY § 4.15 Safety belts. (a) Each operator and passenger occupying any seating position of a motor vehicle in a park area will have the safety belt or child restraint system properly fastened...

  12. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not...

  13. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not...

  14. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not...

  15. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Drive belts. 77.406 Section 77.406 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless...

  16. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Drive belts. 77.406 Section 77.406 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless...

  17. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Drive belts. 77.406 Section 77.406 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless...

  18. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not...

  19. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not...

  20. Grinding Glass Disks On A Belt Sander

    NASA Technical Reports Server (NTRS)

    Lyons, James J., III

    1995-01-01

    Small machine attached to table-top belt sander makes possible to use belt sander to grind glass disk quickly to specified diameter within tolerance of about plus or minus 0.002 in. Intended to be used in place of production-shop glass grinder. Held on driveshaft by vacuum, glass disk rotated while periphery ground by continuous sanding belt.

  1. 30 CFR 77.1107 - Belt conveyors.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Belt conveyors. 77.1107 Section 77.1107 Mineral... § 77.1107 Belt conveyors. Belt conveyors in locations where fire would create a hazard to personnel shall be provided with switches to stop the drive pulley automatically in the event of...

  2. 30 CFR 77.1107 - Belt conveyors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Belt conveyors. 77.1107 Section 77.1107 Mineral... § 77.1107 Belt conveyors. Belt conveyors in locations where fire would create a hazard to personnel shall be provided with switches to stop the drive pulley automatically in the event of...

  3. 30 CFR 77.1107 - Belt conveyors.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Belt conveyors. 77.1107 Section 77.1107 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... § 77.1107 Belt conveyors. Belt conveyors in locations where fire would create a hazard to...

  4. 30 CFR 77.1107 - Belt conveyors.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Belt conveyors. 77.1107 Section 77.1107 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... § 77.1107 Belt conveyors. Belt conveyors in locations where fire would create a hazard to...

  5. 30 CFR 77.1107 - Belt conveyors.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Belt conveyors. 77.1107 Section 77.1107 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... § 77.1107 Belt conveyors. Belt conveyors in locations where fire would create a hazard to...

  6. Short-Term Forecasting of Radiation Belt and Ring Current

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching

    2007-01-01

    A computer program implements a mathematical model of the radiation-belt and ring-current plasmas resulting from interactions between the solar wind and the Earth s magnetic field, for the purpose of predicting fluxes of energetic electrons (10 keV to 5 MeV) and protons (10 keV to 1 MeV), which are hazardous to humans and spacecraft. Given solar-wind and interplanetary-magnetic-field data as inputs, the program solves the convection-diffusion equations of plasma distribution functions in the range of 2 to 10 Earth radii. Phenomena represented in the model include particle drifts resulting from the gradient and curvature of the magnetic field; electric fields associated with the rotation of the Earth, convection, and temporal variation of the magnetic field; and losses along particle-drift paths. The model can readily accommodate new magnetic- and electric-field submodels and new information regarding physical processes that drive the radiation-belt and ring-current plasmas. Despite the complexity of the model, the program can be run in real time on ordinary computers. At present, the program can calculate present electron and proton fluxes; after further development, it should be able to predict the fluxes 24 hours in advance

  7. Whistler anisotropy instabilities as the source of banded chorus: Van Allen Probes observations and particle-in-cell simulations

    SciTech Connect

    Fu, Xiangrong; Cowee, Misa M.; Friedel, Reinhard H.; Funsten, Herbert O.; Gary, S. Peter; Hospodarsky, George B.; Kletzing, Craig; Kurth, William; Larsen, Brian A.; Liu, Kaijun; MacDonald, Elizabeth A.; Reeves, Geoffrey D.; Skoug, Ruth M.; Winske, Dan

    2014-10-22

    Magnetospheric banded chorus is enhanced whistler waves with frequencies ωr < Ωe, where Ωe is the electron cyclotron frequency, and a characteristic spectral gap at ωr ≃ Ωe/2. This paper uses spacecraft observations and two-dimensional particle-in-cell simulations in a magnetized, homogeneous, collisionless plasma to test the hypothesis that banded chorus is due to local linear growth of two branches of the whistler anisotropy instability excited by two distinct, anisotropic electron components of significantly different temperatures. The electron densities and temperatures are derived from Helium, Oxygen, Proton, and Electron instrument measurements on the Van Allen Probes A satellite during a banded chorus event on 1 November 2012. The observations are consistent with a three-component electron model consisting of a cold (a few tens of eV) population, a warm (a few hundred eV) anisotropic population, and a hot (a few keV) anisotropic population. The simulations use plasma and field parameters as measured from the satellite during this event except for two numbers: the anisotropies of the warm and the hot electron components are enhanced over the measured values in order to obtain relatively rapid instability growth. The simulations show that the warm component drives the quasi-electrostatic upper band chorus and that the hot component drives the electromagnetic lower band chorus; the gap at ~Ωe/2 is a natural consequence of the growth of two whistler modes with different properties.

  8. Occurrence characteristics of outer zone relativistic electron butterfly distribution: A survey of Van Allen Probes REPT measurements

    NASA Astrophysics Data System (ADS)

    Ni, Binbin; Zou, Zhengyang; Li, Xinlin; Bortnik, Jacob; Xie, Lun; Gu, Xudong

    2016-06-01

    Using Van Allen Probes Relativistic Electron Proton Telescope (REPT) pitch angle resolved electron flux data from September 2012 to March 2015, we investigate in detail the global occurrence pattern of equatorial (|λ| ≤ 3°) butterfly distribution of outer zone relativistic electrons and its potential correlation with the solar wind dynamic pressure. The statistical results demonstrate that these butterfly distributions occur with the highest occurrence rate ~ 80% at ~ 20-04 magnetic local time (MLT) and L > ~ 5.5 and with the second peak (> ~ 50%) at ~ 11-15 MLT of lower L shells ~ 4.0. They can also extend to L = 3.5 and to other MLT intervals but with the occurrence rates predominantly < ~25%. It is further shown that outer zone relativistic electron butterfly distributions are likely to peak between 58° and 79° for L = 4.0 and 5.0 and between 37° and 58° for L = 6.0, regardless of the level of solar wind dynamic pressure. Relativistic electron butterfly distributions at L = 4.0 also exhibit a pronounced day-night asymmetry in response to the Pdyn variations. Compared to the significant L shell and MLT dependence of the global occurrence pattern, outer zone relativistic electron butterfly distributions show much less but still discernable sensitivity to Pdyn, geomagnetic activity level, and electron energy, the full understanding of which requires future attempts of detailed simulations that combine and differentiate underlying physical mechanisms of the geomagnetic field asymmetry and scattering by various magnetospheric waves.

  9. Whistler anisotropy instabilities as the source of banded chorus: Van Allen Probes observations and particle-in-cell simulations

    DOE PAGES

    Fu, Xiangrong; Cowee, Misa M.; Friedel, Reinhard H.; ...

    2014-10-22

    Magnetospheric banded chorus is enhanced whistler waves with frequencies ωr < Ωe, where Ωe is the electron cyclotron frequency, and a characteristic spectral gap at ωr ≃ Ωe/2. This paper uses spacecraft observations and two-dimensional particle-in-cell simulations in a magnetized, homogeneous, collisionless plasma to test the hypothesis that banded chorus is due to local linear growth of two branches of the whistler anisotropy instability excited by two distinct, anisotropic electron components of significantly different temperatures. The electron densities and temperatures are derived from Helium, Oxygen, Proton, and Electron instrument measurements on the Van Allen Probes A satellite during a bandedmore » chorus event on 1 November 2012. The observations are consistent with a three-component electron model consisting of a cold (a few tens of eV) population, a warm (a few hundred eV) anisotropic population, and a hot (a few keV) anisotropic population. The simulations use plasma and field parameters as measured from the satellite during this event except for two numbers: the anisotropies of the warm and the hot electron components are enhanced over the measured values in order to obtain relatively rapid instability growth. The simulations show that the warm component drives the quasi-electrostatic upper band chorus and that the hot component drives the electromagnetic lower band chorus; the gap at ~Ωe/2 is a natural consequence of the growth of two whistler modes with different properties.« less

  10. L-shell bifurcation of electron outer belt at the recovery phase of geomagnetic storm as observed by STEP-F and SphinX instruments onboard the CORONAS-Photon satellite

    NASA Astrophysics Data System (ADS)

    Dudnik, Oleksiy; Sylwester, Janusz; Kowalinski, Miroslaw; Podgorski, Piotr

    2016-07-01

    Radiation belts and sporadically arising volumes comprising enhanced charged particle fluxes in the Earth's magnetosphere are typically studied by space-borne telescopes, semiconductor, scintillation, gaseous and other types of detectors. Ambient and internal electron bremsstrahlung in hard X-ray arises as a result of interaction of precipitating particles with the atmosphere (balloon experiments) and with the satellite's housings and instrument boxes (orbital experiments). Theses emissions provide a number of new information on the physics of radiation belts. The energies of primary electrons and their spectra responsible for measured X-ray emissions remain usually unknown. Combined measurements of particle fluxes, and their bremsstrahlung by individual satellite instruments placed next to each other provide insight to respective processes. The satellite telescope of electrons and protons STEP-F and the solar X-ray spectrophotometer SphinX were placed in close proximity to each other aboard CORONAS-Photon, the low, circular and highly inclined orbit satellite. Based on joint analysis of the data we detected new features in the high energy particle distributions of the Earth's magnetosphere during deep minimum of solar activity [1-3]. In this research the bifurcation of Van Allen outer electron radiation belt during the weak geomagnetic storm and during passage of interplanetary shock are discussed. Outer belt bifurcation and growth of electron fluxes in a wide energy range were recorded by both instruments during the recovery phase of May 8, 2009 substorm. STEP-F recorded also barely perceptible outer belt splitting on August 5, 2009, after arrival of interplanetary shock to the Earth's magnetosphere bowshock. The STEP-F and SphinX data are compared with the space weather indexes, and with relativistic electron fluxes observed at geostationary orbit. We discuss possible mechanism of the phenomena consisting in the splitting of drift shells because of Earth

  11. Relativistic electron response to the combined magnetospheric impact of a coronal mass ejection overlapping with a high-speed stream: Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Kanekal, S. G.; Baker, D. N.; Henderson, M. G.; Li, W.; Fennell, J. F.; Zheng, Y.; Richardson, I. G.; Jones, A.; Ali, A. F.; Elkington, S. R.; Jaynes, A.; Li, X.; Blake, J. B.; Reeves, G. D.; Spence, H. E.; Kletzing, C. A.

    2015-09-01

    During early November 2013, the magnetosphere experienced concurrent driving by a coronal mass ejection (CME) during an ongoing high-speed stream (HSS) event. The relativistic electron response to these two kinds of drivers, i.e., HSS and CME, is typically different, with the former often leading to a slower buildup of electrons at larger radial distances, while the latter energizing electrons rapidly with flux enhancements occurring closer to the Earth. We present a detailed analysis of the relativistic electron response including radial profiles of phase space density as observed by both Magnetic Electron and Ion Sensor (MagEIS) and Relativistic Electron Proton Telescope instruments on the Van Allen Probes mission. Data from the MagEIS instrument establish the behavior of lower energy (<1 MeV) electrons which span both intermediary and seed populations during electron energization. Measurements characterizing the plasma waves and magnetospheric electric and magnetic fields during this period are obtained by the Electric and Magnetic Field Instrument Suite and Integrated Science instrument on board Van Allen Probes, Search Coil Magnetometer and Flux Gate Magnetometer instruments on board Time History of Events and Macroscale Interactions during Substorms, and the low-altitude Polar-orbiting Operational Environmental Satellites. These observations suggest that during this time period, both radial transport and local in situ processes are involved in the energization of electrons. The energization attributable to radial diffusion is most clearly evident for the lower energy (<1 MeV) electrons, while the effects of in situ energization by interaction of chorus waves are prominent in the higher-energy electrons.

  12. Relativistic Electron Response to the Combined Magnetospheric Impact of a Coronal Mass Ejection Overlapping with a High-Speed Stream: Van Allen Probes Observations

    NASA Technical Reports Server (NTRS)

    Kanekal, S. G.; Baker, D. N.; Henderson, M. G.; Li, W.; Fennell, J. F.; Zheng, Y.; Richardson, I. G.; Jones, A.; Ali, A. F.; Elkington, S. R.; Jaynes, A.; Li, X.; Blake, J. B.; Reeves, G. D.; Spence, H. E.; Kletzing, C. A.

    2015-01-01

    During early November 2013, the magnetosphere experienced concurrent driving by a coronal mass ejection (CME) during an ongoing high-speed stream (HSS) event. The relativistic electron response to these two kinds of drivers, i.e., HSS and CME, is typically different, with the former often leading to a slower buildup of electrons at larger radial distances, while the latter energizing electrons rapidly with flux enhancements occurring closer to the Earth. We present a detailed analysis of the relativistic electron response including radial profiles of phase space density as observed by both Magnetic Electron and Ion Sensor (MagEIS) and Relativistic Electron Proton Telescope instruments on the Van Allen Probes mission. Data from the MagEIS instrument establish the behavior of lower energy (<1 MeV) electrons which span both intermediary and seed populations during electron energization. Measurements characterizing the plasma waves and magnetospheric electric and magnetic fields during this period are obtained by the Electric and Magnetic Field Instrument Suite and Integrated Science instrument on board Van Allen Probes, Search Coil Magnetometer and Flux Gate Magnetometer instruments on board Time History of Events and Macroscale Interactions during Substorms, and the low-altitude Polar-orbiting Operational Environmental Satellites. These observations suggest that during this time period, both radial transport and local in situ processes are involved in the energization of electrons. The energization attributable to radial diffusion is most clearly evident for the lower energy (<1 MeV) electrons, while the effects of in situ energization by interaction of chorus waves are prominent in the higher-energy electrons.

  13. The high-energy proton fluxes in the SAA observed with REM aboard the MIR orbital station

    NASA Technical Reports Server (NTRS)

    Buhler, P.; Zehnder, A.; Kruglanski, M.; Daly, E.; Adams, L.

    2002-01-01

    During two years, from November 1994 to 1996, the particle detector REM measured the highly energetic electron and proton environment at the outside of the MIR orbital station. Using mission averaged data we investigate various aspects of the proton fluxes in the SAA. Comparison with the radiation belt model AP8 reveal important differences. c2002 Elsevier Science Ltd. All rights reserved.

  14. Tectonics of some Amazonian greenstone belts

    NASA Technical Reports Server (NTRS)

    Gibbs, A. K.

    1986-01-01

    Greenstone belts exposed amid gneisses, granitoid rocks, and less abundant granulites along the northern and eastern margins of the Amazonian Craton yield Trans-Amazonican metamorphic ages of 2.0-2.1 Ga. Early proterozoic belts in the northern region probably originated as ensimatic island arc complexes. The Archean Carajas belt in the southeastern craton probably formed in an extensional basin on older continental basement. That basement contains older Archean belts with pillow basalts and komatiites. Belts of ultramafic rocks warrant investigatijon as possible ophiolites. A discussion follows.

  15. Cosmic Ray Mantle Visibility on Kuiper Belt Objects

    NASA Technical Reports Server (NTRS)

    Cooper, John F.; Hill, Matt E.; Richardson, J. D.; Sturner, S. J.

    2006-01-01

    Optically red objects constitute the dynamically cold, old component of the Classical Kuiper Belt (40 - 47 AU) with heliocentric orbits of low eccentricity and inclination. The red colors likely arise from primordial mixed ices processed by irradiation to meters in surface depth over the past four billion years, since the time of giant planet migration and Kuiper Belt stirring, at relatively moderate dosages of 60 gigarads provided by galactic cosmic ray protons and heavier ions. The red cosmic ray mantle is uniformly visible on the cold classical objects beneath a minimally thin eroded layer of more neutrally colored material arising from cumulative effects of heliospheric particle irradiation. The radiation fluxes are lowest in the middle heliospheric region containing the Classical Kuiper Belt and increase from there both towards and away from the Sun. Despite increasing irradiation at various times of solar system history from increases in solar and interstellar ion fluxes, the red object region has apparently never reached sufficiently high dosage levels to neutralize in color the red mantle material. Erosion processes, including plasma sputtering and micrometeroid impacts, act continuously to reduce thickness of the upper neutral crust and expose the cosmic ray mantle. A deeper layer at tens of meters and more may consist of relatively unprocessed ices that can erupt to the surface by larger impacts or cryovolcanism and account for brighter surfaces of larger objects such as 2003 UB313. Surface colors among the Kuiper Belt and other icy objects of the outer solar system are then a function, assuming uniform primordial composition, of relative thickness for the three layers and of the resurfacing age dependent on the orbital and impact history of each object.

  16. Automated determination of electron density from electric field measurements on the Van Allen Probes spacecraft

    NASA Astrophysics Data System (ADS)

    Zhelavskaya, Irina; Kurth, William; Spasojevic, Maria; Shprits, Yuri

    2016-07-01

    We present the Neural-network-based Upper-hybrid Resonance Determination (NURD) algorithm for automatic inference of the electron number density from plasma wave measurements made onboard NASA's Van Allen Probes mission. A feedforward neural network is developed to determine the upper hybrid resonance frequency, f_{uhr}, from electric field measurements, which is then used to calculate the electron number density. In previous missions, the plasma resonance bands were manually identified, and there have been few attempts to do robust, routine automated detections. We describe the design and implementation of the algorithm and perform an initial analysis of the resulting electron number density distribution obtained by applying NURD to 2.5 years of data collected with the EMFISIS instrumentation suite of the Van Allen Probes mission. Densities obtained by NURD are compared to those obtained by another recently developed automated technique and also to an existing empirical plasmasphere and trough density model.

  17. Cycloaddition reactions of allenes with N-phenylmaleimide. A two-step, diradical-intermediate process

    SciTech Connect

    Pasto, D.J.; Heid, P.F.; Warren, S.E.

    1982-06-30

    The stereoselectivities, chemoselectivities, relative reactivities, and kinetic isotope effects have been determined in the cycloaddition reactions of substituted allenes with N-phenylmaleimide. The comparison of these results with those derived from the studies of the cycloaddition of 1,1-dichloro-2,2-difluoroethene and the radical-chain addition of benzenethiol to allenes strongly indicates that the cycloadditions with N-phenylmaleimide occur via a two-step, diradical-intermediate process. The stereochemical features controlling the formation of the stereoisomeric diradical intermediates and their ring closures are discussed. In addition to the cycloaddition processes, competitive ene reactions occur to produce intermediate dienes, which react further to produce 1:2 adducts or nonreactive alkyne-containing 1:1 adducts. These ene reactions also appear to proceed via diradical intermediates.

  18. LANL LDRD-funded project: Test particle simulations of energetic ions in natural and artificial radiation belts

    SciTech Connect

    Cowee, Misa; Liu, Kaijun; Friedel, Reinhard H.; Reeves, Geoffrey D.

    2012-07-17

    We summarize the scientific problem and work plan for the LANL LDRD-funded project to use a test particle code to study the sudden de-trapping of inner belt protons and possible cross-L transport of debris ions after a high altitude nuclear explosion (HANE). We also discuss future application of the code for other HANE-related problems.

  19. Characterizing radiation belt electron precipitation losses using BARREL (Balloon Array for RBSP Relativistic Electron Losses) data.

    NASA Astrophysics Data System (ADS)

    Bowers, G. S.; Smith, D. M.; Millan, R. M.; Sample, J. G.; McCarthy, M.; Woodger, L. A.; Halford, A. J.; Liang, X.

    2015-12-01

    Precipitation loss is a process whereby charged particles trapped in the radiation belts scatter into the Earth's atmosphere and are removed from the belt population. Balloon-borne x-ray detectors and satellites like SAMPEX have generally observed precipitation losses of three types, here characterized by their MLT distribution and related e-folding energy of the inferred precipitating electron energy spectrum, the third characterized by its burstiness and brief duration: soft (isotropic in MLT with e-folding for balloons between 50-100 keV, for SAMPEX between 100-300 keV), hard (concentrated in the dusk-to-midnight sector with e-folding for balloons > 200 keV, for SAMPEX > 400 keV), and microbursts (concentrated in the dawn-to-noon sector, bursty and very short temporal structure < 1s). Soft precipitation occurs much more often than the others, but has received less attention in the literature even though recent analysis of observed SAMPEX losses has shown that soft precipitation may account for the greatest electron loss from the quiet time radiation belts. The goal of this project is to compare/reconcile the different spectral characterizations of soft precipitation observed by BARREL and SAMPEX, and seek to understand the wave scattering mechanisms responsible for these losses.For this work we will present the 2013/2014 observed BARREL precipitation events cataloged according to type, (soft, hard, microburst), MLT and L distribution, and geomagnetic/space weather conditions. In particular, we will use Van Allen Probe data to define the state of the belts and the position of the balloon relative to the plasmapause and trapping boundary before and after precipitation events.

  20. Radiation Belts Storage Ring : What the Cluster-CIS data can tell us

    NASA Astrophysics Data System (ADS)

    Dandouras, I. S.; Ganushkina, N.; Amariutei, O. A.; Reme, H.

    2013-12-01

    Following the launch by NASA of the Radiation Belt Storm Probes (RBSP) twin spacecraft, now named the Van Allen Probes, the discovery of a storage ring was announced: Baker et al., Science, 2013. This transient feature was observed during September 2012, following the arrival of an interplanetary shock, was located between L=3.0 and L=3.5 and consisted of about 4 to 6 MeV electrons. During that period the Cluster spacecraft had a high-inclination orbit, with a perigee just above 2 Re. The CIS experiment onboard Cluster is sensitive to penetrating energetic electrons (E > 2 MeV), which produce background counts and thus allow to localize the boundaries of the outer and inner radiation belts (Ganushkina et al., JGR, 2011). A search was undertaken in the September 2012 CIS data for eventual signatures of the storage ring, and indeed a small increase of the instrument background was observed between L=3.0 and L=3.5. This is clearly separated from the main outer radiation belt, which presents a much stronger background due to higher fluxes of relativistic electrons. A mono-energetic ion drift band was also observed by CIS inside the storage ring, at about 5 keV for He+ and O+ ions. This result provides an independent confirmation for the storage ring. In addition, it allows also to examine Cluster and Double Star data from earlier years, covering a full solar cycle, for other such signatures of a transient storage ring. It results that this 3-belt structure is seen several times.

  1. Source of O+ in the ring current: Van Allen Probes observations during the 1 June 2013 storm

    NASA Astrophysics Data System (ADS)

    Yang, J.; Song, P.; Burke, W. J.; Zhang, J.; Noah, M.; Larsen, B.; Spence, H. E.; Reeves, G. D.

    2014-12-01

    During magnetic storms, the concentration of O+ ions in the ring current can increase substantially. The mechanisms that energize these O+ ions so that they gain enough energy to escape from the ionosphere into the magnetosphere have long been debated. The highly sensitive HOPE (Helium, Oxygen, Proton, and Electron) instrument onboard the Van Allen Probe satellites provide an opportunity to investigate this problem. The two satellites are in nearly identical highly-elliptical, low-inclination (~10°) orbits with a perigee of 1.1 Earth radii (RE), an apogee of 5.8 RE, and a period of ~9 hours. We study a storm event whose SSC occurred near 15:00 UT on 31 May 2013 followed by a lengthy initial phase. The main phase began early on 1 June, reaching a Sym-H minimum of - 134 nT at 07:54 UT. We have identified a large energetic proton enhancement event which is marked by a significant increase in the fluxes of high-energy ions in the deep portion of the main phase. We concentrate on the relative dynamics of H+ and O+. From 03:00 UT to 06:50 UT, there were a few quasi-periodic enhancements of O+ fluxes in the 200 eV to 3.5 keV energy range. A Fourier analysis shows clear power around 30 min periods and excellent coherence among these channels. These enhancements further show clear dispersion with high-energy channels increasing first followed by lower energy channels. During the event, the satellites were near the apogee in the pre-midnight local time sector. The location of the source region can be inferred by energy dispersion based on the time-of-flight effect. One may show that if the particles in different energies were produced at the same time and location, time is linearly correlated with the reciprocal of square-root of the energy for the enhanced fluxes and the source distance can be derived by the slope of the lines of enhanced fluxes. During the event, we identified 8 such enhancements. The sources of these O+ ions appear to be from similar distance to the

  2. Ruthenium Catalyzed Reductive Coupling of Paraformaldehyde to Trifluoromethyl Allenes: CF3-Bearing All-Carbon Quaternary Centers

    PubMed Central

    Sam, Brannon; Montgomery, T. Patrick; Krische, Michael J.

    2013-01-01

    Trifluoromethyl substituted allenes engage in ruthenium catalyzed reductive couplings with paraformaldehyde to form products of hydrohydroxymethylation as single regioisomers. This method enables generation of CF3-bearing all-carbon quaternary stereocenters. PMID:23841678

  3. A critique of Mark D. Allen's "the preservation of verb subcategory knowledge in a spoken language comprehension deficit".

    PubMed

    Kemmerer, David

    2008-07-01

    Allen [Allen, M. (2005). The preservation of verb subcategory knowledge in a spoken language comprehension deficit. Brain and Language, 95, 255-264.] reports a single patient, WBN, who, during spoken language comprehension, is still able to access some of the syntactic properties of verbs despite being unable to access some of their semantic properties. Allen claims that these findings challenge linguistic theories which assume that much of the syntactic behavior of verbs can be predicted from their meanings. I argue, however, that this conclusion is not supported by the data for two reasons: first, Allen focuses on aspects of verb syntax that are not claimed to be influenced by verb semantics; and second, he ignores aspects of verb syntax that are claimed to be influenced by verb semantics.

  4. Enantioselective and Regiodivergent Addition of Purines to Terminal Allenes: Synthesis of Abacavir.

    PubMed

    Thieme, Niels; Breit, Bernhard

    2017-02-01

    The rhodium-catalyzed atom-economic asymmetric N-selective intermolecular addition of purine derivatives to terminal allenes is reported. Branched allylic purines were obtained in high yields, regioselectivity and outstanding enantioselectivity utilizing a Rh/Josiphos catalyst. Conversely, linear selective allylation of purines could be realized in good to excellent regio- and E/Z-selectivity with a Pd/dppf catalyst system. Furthermore, the new methodology was applied to a straightforward asymmetric synthesis of carbocyclic nucleoside abacavir.

  5. Astronauts Gardner and Allen during loading of Palapa B-2 in payload bay

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Joseph P. Allen, in this frame, is the sole anchor for the top portion (and most of) the captured Palapa B-2 satellite. Astronaut Dale A. Gardner is on the other end as they load it into the payload bay. Note the difference between the two stinger devices stowed on the Challenger's port side (right side of frame). The one nearer the spacecraft's vertical stabilizer is spent. The one nearer the camera is still awaiting use.

  6. Allene as the parent substrate in zinc-mediated biomimetic hydration reactions of cumulenes.

    PubMed

    Jahn, Burkhard O; Eger, Wilhelm A; Anders, Ernst

    2008-11-07

    The aim of our present investigation is to unravel the general mode of biomimetic activation of a wide variety of cumulenes by carbonic anhydrase (CA) models. Carbonic anhydrases allow the specific recognition, activation and transfer not only of CO2 but also of heteroallenes X=C=Y such as the polar or polarizable examples COS, CS2, H2CCO, and RNCS. Therefore, this enzyme class fulfils the requirements of excellent catalysts with a wide variety of important applications. Can this be extended to the isoelectronic but less reactive allene molecule, H2C=C=CH2 and extremely simplified models as mimetic concept for active center of the carbonic anhydrase? Allene is a waste product in the refinery, i.e. the C3-cut of the naphtha distillation; therefore, any addition product that can be obtained from allene in high yields will be of significant value. We investigated the complete catalytic cycle of a very simple model reaction, the hydration of allene, using density functional theory. Additionally, calculations were performed for the uncatalyzed reaction. There are two possible ways for the nucleophilic attack leading to different products. The zinc hydroxide complex and the water molecule can react at the central or the terminal carbon atoms (positional selectivity), the resulting products are 2-propen-1-ol and propen-2-ol, respectively, acetone. The calculations indicate a significant lower energy barrier for the rate determining step of the formation of propen-2-ol and therefore a well-expressed regioselectivity for the addition of such small molecules. The zinc complex has a pronounced catalytic effect and lowers the activation barrier from 262.5 to 123.9 kJ/mol compared with the uncatalyzed reaction. This work suggests the most probable paths for this reaction and discloses the necessity for the development of novel catalysts.

  7. Palladium-Catalyzed Formal (5 + 2) Annulation between ortho-Alkenylanilides and Allenes.

    PubMed

    Cendón, Borja; Casanova, Noelia; Comanescu, Cezar; García-Fandiño, Rebeca; Seoane, Andrés; Gulías, Moisés; Mascareñas, José L

    2017-04-07

    2-Alkenyltriflylanilides react with allenes upon treatment with catalytic amounts of Pd(OAc)2 and Cu(II) to give highly valuable 2,3-dihydro-1H-benzo[b]azepines, in good yields, and with very high regio- and diastereoselectivities. Density functional theory (DFT) calculations suggest that the C-H activation of the alkenylanilide involves a classical concerted metalation-deprotonation (CMD) mechanism.

  8. A radiation belt monitor for the High Energy Transient Experiment Satellite

    NASA Technical Reports Server (NTRS)

    Lo, D. H.; Wenzel, K. W.; Petrasso, R. D.; Prigozhin, G. Y.; Doty, J.; Ricker, G.

    1993-01-01

    A Radiation Belt Monitor (RBM) sensitive to protons and electrons with energy approximately greater than 0.5 MeV has been designed for the High Energy Transient Experiment (HETE) satellite in order to: first, control the on-off configuration of the experiments (i.e. those susceptible to proton damage); and second, to indicate the presence of proton and/or electron events that could masquerade as legitimate high energy photon events. One of the two RBM channels has an enhanced sensitivity to electrons. Each channel of the RBM, based on a PIN silicon diode, requires a typical power of 6 milliwatts. Tests have been performed with protons with energies from approximately 0.1 to 2.5 MeV (generated by a Cockcroft-Walton linear accelerator via the d(d,p)t reaction), and with electrons with energies up to 1 MeV (from a 1.0 microcurie Bi-207 source).

  9. Deep Dielectric Charging of Spacecraft Polymers by Energetic Protons

    NASA Technical Reports Server (NTRS)

    Green, Nelson W.; Dennison, J. R.

    2007-01-01

    The majority of research in the field of spacecraft charging concentrates on electron charging effects with little discussion of charging by protons. For spacecraft orbiting in the traditional LEO and GEO environments this emphasis on electrons is appropriate since energetic electrons are the dominant species in those orbits. But for spacecraft in orbits within the inner radiation belts or for interplanetary and lunar space probes, proton charging (center dot) effects may also be of concern. To examine bulk spacecraft charging effects in these environments several typical highly insulating spacecraft polymers were exposed to energetic protons (center dot) with energies from 1 Me V to lO Me V to simulate protons from the solar wind and from solar energetic proton events. Results indicate that effects in proton charged dielectrics are distinctly different than those observed due to electron charging. In most cases, the positive surface potential continued to increase for periods on the order of minutes to a day, followed by long time scale decay at rates similar to those observed for electron charging. All samples charged to positive potentials with substantially lower magnitudes than for equivalent electron doses. Possible explanations for the different behavior of the measured surface potentials from proton irradiation are discussed; these are related to the evolving internal charge distribution from energy dependent electron and proton transport, electron emission, charge migration due to dark current and radiation induced conductivity, and electron capture by embedded protons.

  10. Allen Brain Atlas-Driven Visualizations: a web-based gene expression energy visualization tool.

    PubMed

    Zaldivar, Andrew; Krichmar, Jeffrey L

    2014-01-01

    The Allen Brain Atlas-Driven Visualizations (ABADV) is a publicly accessible web-based tool created to retrieve and visualize expression energy data from the Allen Brain Atlas (ABA) across multiple genes and brain structures. Though the ABA offers their own search engine and software for researchers to view their growing collection of online public data sets, including extensive gene expression and neuroanatomical data from human and mouse brain, many of their tools limit the amount of genes and brain structures researchers can view at once. To complement their work, ABADV generates multiple pie charts, bar charts and heat maps of expression energy values for any given set of genes and brain structures. Such a suite of free and easy-to-understand visualizations allows for easy comparison of gene expression across multiple brain areas. In addition, each visualization links back to the ABA so researchers may view a summary of the experimental detail. ABADV is currently supported on modern web browsers and is compatible with expression energy data from the Allen Mouse Brain Atlas in situ hybridization data. By creating this web application, researchers can immediately obtain and survey numerous amounts of expression energy data from the ABA, which they can then use to supplement their work or perform meta-analysis. In the future, we hope to enable ABADV across multiple data resources.

  11. Magnetospheric dynamics of trapped solar proton events

    NASA Astrophysics Data System (ADS)

    Larsen, B. A.; Engel, M.; Chen, Y.; Friedel, R. H.

    2012-12-01

    Solar proton events (SEP) are sometimes trapped in the magnetosphere creating a new trapped belt or protons in the L=3 to L=4 range that can last for months. We note that there is a commonly observed and unexplained time gap between the SEP event and flux being observed in the L=3 to L=4 trapping region from the POES spacecraft. We present two hypotheses to explain the time gap and explore each. First the SEP trapping mechanism is thought to be driven by interplanetary shocks, required to drive the protons deep into the magnetosphere to regions where geomagnetic shielding does not normally grant them access where they then can become trapped. The processes that drive the protons are highly peaked at equatorial pitch angles near 90 degrees explaining the time gap as the time required for pitch angle diffusion to change the particles to pitch angles observable by POES in low-Earth orbit. The second hypothesis is that the time gap is the result of radial transport preserving the first adiabatic invariant thus energizing the protons from one energy channel to another. The time gap is then the time required for radial transport to move and energize the particles into the L=3 to L=4 region. Evidence and conclusions about each hypothesis is presented.

  12. Solar Modulation of Inner Trapped Belt Radiation Flux as a Function of Atmospheric Density

    NASA Technical Reports Server (NTRS)

    Lodhi, M. A. K.

    2005-01-01

    No simple algorithm seems to exist for calculating proton fluxes and lifetimes in the Earth's inner, trapped radiation belt throughout the solar cycle. Most models of the inner trapped belt in use depend upon AP8 which only describes the radiation environment at solar maximum and solar minimum in Cycle 20. One exception is NOAAPRO which incorporates flight data from the TIROS/NOAA polar orbiting spacecraft. The present study discloses yet another, simple formulation for approximating proton fluxes at any time in a given solar cycle, in particular between solar maximum and solar minimum. It is derived from AP8 using a regression algorithm technique from nuclear physics. From flux and its time integral fluence, one can then approximate dose rate and its time integral dose.

  13. Proton radiography to improve proton therapy treatment

    NASA Astrophysics Data System (ADS)

    Takatsu, J.; van der Graaf, E. R.; Van Goethem, M.-J.; van Beuzekom, M.; Klaver, T.; Visser, J.; Brandenburg, S.; Biegun, A. K.

    2016-01-01

    The quality of cancer treatment with protons critically depends on an accurate prediction of the proton stopping powers for the tissues traversed by the protons. Today, treatment planning in proton radiotherapy is based on stopping power calculations from densities of X-ray Computed Tomography (CT) images. This causes systematic uncertainties in the calculated proton range in a patient of typically 3-4%, but can become even 10% in bone regions [1,2,3,4,5,6,7,8]. This may lead to no dose in parts of the tumor and too high dose in healthy tissues [1]. A direct measurement of proton stopping powers with high-energy protons will allow reducing these uncertainties and will improve the quality of the treatment. Several studies have shown that a sufficiently accurate radiograph can be obtained by tracking individual protons traversing a phantom (patient) [4,6,10]. Our studies benefit from the gas-filled time projection chambers based on GridPix technology [2], developed at Nikhef, capable of tracking a single proton. A BaF2 crystal measuring the residual energy of protons was used. Proton radiographs of phantom consisting of different tissue-like materials were measured with a 30×30 mm2 150 MeV proton beam. Measurements were simulated with the Geant4 toolkit.First experimental and simulated energy radiographs are in very good agreement [3]. In this paper we focus on simulation studies of the proton scattering angle as it affects the position resolution of the proton energy loss radiograph. By selecting protons with a small scattering angle, the image quality can be improved significantly.

  14. Ring current and radiation belts

    NASA Technical Reports Server (NTRS)

    Williams, D. J.

    1987-01-01

    Studies performed during 1983-1986 on the ring current, the injection boundary model, and the radiation belts are discussed. The results of these studies yielded the first observations on the composition and charge state of the ring current throughout the ring-current energy range, and strong observational support for an injection-boundary model accounting for the origins of radiation-belt particles, the ring current, and substorm particles observed at R less than about 7 earth radii. In addition, the results have demonstrated that the detection of energetic neutral atoms generated by charge-exchange interactions between the ring current and the hydrogen geocorona can provide global images of the earth's ring current and its spatial and temporal evolution.

  15. Beyond the Kuiper Belt Edge

    NASA Astrophysics Data System (ADS)

    Sheppard, Scott

    2012-06-01

    Of the thousands of known objects beyond Neptune, only one has a perihelion significantly beyond 50 AU, Sedna at 75 AU. Kuiper Belt surveys to date have not been optimized to survey beyond the Kuiper Belt edge at 50 AU. Most of these surveys either did not go faint enough, did not have the required long cadence to detect very slow moving objects or covered too small of an area of sky. The dynamical and physical properties of objects in this region offer key constraints on the formation and evolution of our solar system. In order to probe the Sedna like population of objects with moderate radii (100 km) we propose a deep wide-field outer solar system survey. This survey will allow us to determine if the objects beyond 50 AU are fainter than expected, if there is truly a dearth of objects, or if the Kuiper Belt continues again after some sizable gap possibly caused by a planet sized object. We will be able to examine the origin of Sedna and determine if this eccentric, distant body is unique (as once believed for Pluto) or just the first of a new class of object in the outer Solar System. We will also explore the Neptune Trojans and scattered disk populations through the survey.

  16. Beyond the Kuiper Belt Edge

    NASA Astrophysics Data System (ADS)

    Sheppard, Scott

    2011-01-01

    Of the thousands of known objects beyond Neptune, only one has a perihelion significantly beyond 50 AU, Sedna at 75 AU. Kuiper Belt surveys to date have not been optimized to survey beyond the Kuiper Belt edge at 50 AU. Most of these surveys either did not go faint enough, did not have the required long cadence to detect very slow moving objects or covered too small of an area of sky. The dynamical and physical properties of objects in this region offer key constraints on the formation and evolution of our solar system. In order to probe the Sedna like population of objects with moderate radii (100 km) we propose a deep wide-field outer solar system survey. This survey will allow us to determine if the objects beyond 50 AU are fainter than expected, if there is truly a dearth of objects, or if the Kuiper Belt continues again after some sizable gap possibly caused by a planet sized object. We will be able to examine the origin of Sedna and determine if this eccentric, distant body is unique (as once believed for Pluto) or just the first of a new class of object in the outer Solar System. We will also explore the Neptune Trojans and scattered disk populations through the survey.

  17. Beyond the Kuiper Belt Edge

    NASA Astrophysics Data System (ADS)

    Sheppard, Scott; Trujillo, Chad

    2012-02-01

    Of the thousands of known objects beyond Neptune, only one has a perihelion significantly beyond 50 AU, Sedna at 75 AU. Kuiper Belt surveys to date have not been optimized to survey beyond the Kuiper Belt edge at 50 AU. Most of these surveys either did not go faint enough, did not have the required long cadence to detect very slow moving objects or covered too small of an area of sky. The dynamical and physical properties of objects in this region offer key constraints on the formation and evolution of our solar system. In order to probe the Sedna like population of objects with moderate radii (100 km) we propose a medium wide-field outer solar system survey. This survey will allow us to determine if the objects beyond 50 AU are fainter than expected, if there is truly a dearth of objects, or if the Kuiper Belt continues again after some sizable gap possibly caused by a planet sized object. We will be able to examine the origin of Sedna and determine if this eccentric, distant body is unique (as once believed for Pluto) or just the first of a new class of object in the outer Solar System.

  18. Liquid belt radiator design study

    NASA Technical Reports Server (NTRS)

    Teagan, W. P.; Fitzgerald, K. F.

    1986-01-01

    The Liquid Belt Radiator (LBR) is an advanced concept developed to meet the needs of anticipated future space missions. A previous study documented the advantages of this concept as a lightweight, easily deployable alternative to present day space heat rejection systems. The technical efforts associated with this study concentrate on refining the concept of the LBR as well as examining the issues of belt dynamics and potential application of the LBR to intermediate and high temperature heat rejection applications. A low temperature point design developed in previous work is updated assuming the use of diffusion pump oil, Santovac-6, as the heat transfer media. Additional analytical and design effort is directed toward determining the impact of interface heat exchanger, fluid bath sealing, and belt drive mechanism designs on system performance and mass. The updated design supports the earlier result by indicating a significant reduction in system specific system mass as compared to heat pipe or pumped fluid radiator concepts currently under consideration (1.3 kg/sq m versus 5 kg/sq m).

  19. V-belt assembly for transmitting power

    SciTech Connect

    Okawa, S.; Ogino, I.; Okuwaki, S.

    1987-02-24

    This patent describes a V-belt assembly trained over V-belt wheels for transmitting power comprising: a flexible endless belt; rigid suspension members secured fixedly to the endless belt perpendicularly to the longitudinal direction of the endless belt and having pivotal projections extending from opposite sides thereof; substantially U-shaped rigid transmission pieces having holes formed therein wherein the pivotal projections extending from the respective suspension members extend in sidewise directions and into the holes so as to allow for relative movement between each of the pivotal projections and the hole for engaging V-shaped grooves of the V-belt wheels. A center axis of the pivotal projection passes through an approximately central portion of thickness of the endless belt. Each of the suspension members is substantially U-shaped so as to surround one bottom surface and opposite side surfaces of the endless belt and is secured fixedly to the endless belt; and an opposed plate connected to each of the suspension members and positioned against a bottom surface of the endless belt opposite the one bottom surface.

  20. [A study on Horace N. Allen's medicine and recognition of Korean body].

    PubMed

    Lee, Young Ah

    2011-12-31

    Je Jung Won was the first modern-style Government hospital built by the Korean King Ko-Jong in April 1885, and it was the medical missionary Horace Newton Allen(1858~1932) who made one of the greatest contributions to the establishment of the hospital. Allen was an American missionary. He graduated from Ohio Wesleyan University with a degree in theology in 1881, and completed one-yearcourse at Miami Medical College. In Korea and America he worked as a physician, a missionary, an American diplomatic minister to Korea and a Korean minister's secretary to America. While acting as a mediator between Korea and America, he knew and recorded the domestic and foreign situation of Korea during Gaehwagi(the civilized and enlightened age). Thus to study him is to understand Korea's Gaehwagi as well as to research American medical missionaries. During his stay in Korea(1884~1905), Allen steadily wrote diaries and letters about Korean politics, diplomacy, society, culture, and medicine. Thus his public/private record through diaries and letters(the quantity of these materials amounts to several thousands) supplements the Korean early modern era's historical record. However, until now these materials have received little scholarly attention from researchers except for a few historians of missionary work between Korea and America, or of Korean modern medicine. I intended to use these materials to suggest a new perspective on the study of Korean Gaehwagi. Allen, along with John W. Heron, who came to Seoul on June 21st 1885, treated about 10,460 Korean patients in the first year of the opening of JeJungWon. They made "the first annual report of the Korean Government Hospital". This report explained how Allen and Heron regarded and treated Korean patients. Allen's diaries, letters and other writings offer a realistic view of how the western people actually recognized the Korean people at that time. As a western doctor, Allen had an ambivalent attitude toward Korean medical concepts

  1. Development of a new Global RAdiation Belt model: GRAB

    NASA Astrophysics Data System (ADS)

    Sicard-Piet, Angelica; Lazaro, Didier; Maget, Vincent; Rolland, Guy; Ecoffet, Robert; Bourdarie, Sébastien; Boscher, Daniel; Standarovski, Denis

    2016-07-01

    The well known AP8 and AE8 NASA models are commonly used in the industry to specify the radiation belt environment. Unfortunately, there are some limitations in the use of these models, first due to the covered energy range, but also because in some regions of space, there are discrepancies between the predicted average values and the measurements. Therefore, our aim is to develop a radiation belt model, covering a large region of space and energy, from LEO altitudes to GEO and above, and from plasma to relativistic particles. The aim for the first version is to correct the AP8 and AE8 models where they are deficient or not defined. At geostationary, we developed ten years ago for electrons the IGE-2006 model which was proven to be more accurate than AE8, and used commonly in the industry, covering a broad energy range, from 1keV to 5MeV. From then, a proton model for geostationary orbit was also developed for material applications, followed by the OZONE model covering a narrower energy range but the whole outer electron belt, a SLOT model to asses average electron values for 2proton flux values at low altitudes. As most of these models were developed using more than a solar cycle of measurements, these measurements being checked, cross calibrated and filtered, we have no doubt that the obtained averages are more accurate than AP8 and AE8 for these particular locations. These local models were validated along different orbit with independent data sets or effect measurements. We will use a cache file system to switch between models, in order to obtain at each location in space and energy point the most reliable value. Of course, the way the model is developed is well suited to add new local developments or to include international partnership. This model will be called the GRAB model, as Global Radiation Belt model. We will present first beta version during this conference.

  2. Synchrotron based proton drivers

    SciTech Connect

    Weiren Chou

    2002-09-19

    Proton drivers are the proton sources that produce intense short proton bunches. They have a wide range of applications. This paper discusses the proton drivers based on high-intensity proton synchrotrons. It gives a review of the high-intensity proton sources over the world and a brief report on recent developments in this field in the U.S. high-energy physics (HEP) community. The Fermilab Proton Driver is used as a case study for a number of challenging technical design issues.

  3. Energetic Particles and Magnetic Fields in the Earth’s Magnetosphere and Interplanetary Space

    DTIC Science & Technology

    1997-09-30

    in preparation) (support by ONR). J. A. Van Allen, 1994. “ Kuiper Prize Lecture: Electrons, protons, and planets,” Icarus, 122, 209- 232, 1996 (partial...302-309 (partial support by ONR). J. A. Van Allen, 1996. “Radiation belt ,” in Macmillan Encyclopedia of Physics, New York, Vol. 3, pp. 1321-1322

  4. Lighting-induced Electron Precipitation (LEP) Events versus Geomagnetic Activity: A Probe Tool to Re-Evaluate the Electron Radiation Belt Loss Mechanisms (P16)

    NASA Astrophysics Data System (ADS)

    Fernandez, J. H.; Raulin, J.-P.; Correia, E.; Brum, C. G. M.

    2006-11-01

    We present the first results of an incipient attempt to re-model the Van Allen electron radiation belts equilibrium mechanisms. During the 23rd cycle solar minimum period (1995-1997) the Lightning- induced Electron Precipitation (LEP) events (electron precipitation from the geo-space to the upper Earth atmosphere) occurrence at the Antarctica Peninsula region was collected and studied. With statistical techniques we have reproduced the pattern of the events incidence during that period. The year 1998 was also analyzed and two well-defined geomagnetic storms (01-07 May and 26-31 Aug) were studied in association with the Trimpi events data. We have confirmed the narrow relationship between events occurrence rate and geomagnetic activity. The next step, in order to carry on the model, will be the modeling of the solar maximum LEP occurrence and to compute these results in the present radiation belts population models.

  5. Synchronous and Cogged Fan Belt Performance Assessment

    SciTech Connect

    Cutler, D.; Dean, J.; Acosta, J.

    2014-02-01

    The GSA Regional GPG Team commissioned the National Renewable Energy Laboratory (NREL) to perform monitoring of cogged V-belts and synchronous belts on both a constant volume and a variable air volume fan at the Byron G. Rodgers Federal Building and U.S. Courthouse in Denver, Colorado. These motor/fan combinations were tested with their original, standard V-belts (appropriately tensioned by an operation and maintenance professional) to obtain a baseline for standard operation. They were then switched to the cogged V-belts, and finally to synchronous belts. The power consumption by the motor was normalized for both fan speed and air density changes. This was necessary to ensure that the power readings were not influenced by a change in rotational fan speed or by the power required to push denser air. Finally, energy savings and operation and maintenance savings were compiled into an economic life-cycle cost analysis of the different belt options.

  6. Direct comparison of transient radiation belt topology and dynamics in 1991 based on measurements onboard Mir space station and NOAA satellite.

    PubMed

    Shurshakov, V A; Huston, S L; Dachev TsP; Petrov, V M; Ivanov YuV; Semkova, J V

    1998-01-01

    In March 1991 the CRRES spacecraft measured a new transient radiation belt resulting from a solar proton event and subsequent geomagnetic disturbance. The presence of this belt was also noted by dosimeter-radiometers aboard the Mir space station (approx. 400 km, 51 degrees orbit) and by particle telescopes on the NOAA-10 spacecraft (850 km, 98 degrees). This event provides a unique opportunity to compare particle flux and dose measurements made by different instruments in different orbits under changing conditions. We present here a comparison of the measurements made by the different detectors. We discuss the topology and dynamics of the transient radiation belt over a period of more than one year.

  7. Proton Therapy - Accelerating Protons to Save Lives

    SciTech Connect

    Keppel, Cynthia

    2011-10-25

    In 1946, physicist Robert Wilson first suggested that protons could be used as a form of radiation therapy in the treatment of cancer because of the sharp drop-off that occurs on the distal edge of the radiation dose. Research soon confirmed that high-energy protons were particularly suitable for treating tumors near critical structures, such as the heart and spinal column. The precision with which protons can be delivered means that more radiation can be deposited into the tumor while the surrounding healthy tissue receives substantially less or, in some cases, no radiation. Since these times, particle accelerators have continuously been used in cancer therapy and today new facilities specifically designed for proton therapy are being built in many countries. Proton therapy has been hailed as a revolutionary cancer treatment, with higher cure rates and fewer side effects than traditional X-ray photon radiation therapy. Proton therapy is the modality of choice for treating certain small tumors of the eye, head or neck. Because it exposes less of the tissue surrounding a tumor to the dosage, proton therapy lowers the risk of secondary cancers later in life - especially important for young children. To date, over 80,000 patients worldwide have been treated with protons. Currently, there are nine proton radiation therapy facilities operating in the United States, one at the Hampton University Proton Therapy Institute. An overview of the treatment technology and this new center will be presented.

  8. Comparing Local-Time and Storm-Phase Distributions of EMIC Waves Observed by Van Allen Probes A, GOES-13, and Halley, Antarctica

    NASA Astrophysics Data System (ADS)

    Ohnsted, M.; Engebretson, M. J.; Posch, J. L.; Lessard, M.; Singer, H. J.; Kletzing, C.; Smith, C. W.; Horne, R. B.

    2015-12-01

    Electromagnetic ion cyclotron (EMIC) waves are expected to be highly efficient in depleting the ring current and in removing outer radiation belt electrons. However, the distribution of these waves in subauroral regions has not been well characterized. In this study we present 0-5 Hz magnetic field data from the Van Allen Probes A (RBSP A) spacecraft (in elliptical equatorial orbit with apogee at 5.8 RE), 0-1 Hz data from GOES-13 (in geosynchronous orbit), and 0-5 Hz data from Halley, Antarctica (L ~4.6), during the first full local-time precession of the Van Allen Probes from October 2012 through July 2014. The considerably different hourly local time vs. L distributions observed point to distinct locations and geomagnetic activity-dependent patterns of EMIC wave activity. GOES-13 wave occurrences exhibited a broad peak in the noon-to-dusk sector. He+ band events peaked near dusk, while H+ band waves peaked near noon, with a secondary peak centered near dawn. More EMIC waves occurred during storm main phase in the He+ band (5%) than in the H+ band (1%), and 80% and 89% of the He+ and H+ band waves, respectively, occurred under late storm recovery or quiet conditions. During all storm phases the local time occurrence patterns of < 0.4 Hz and 0.4-1.0 Hz events at Halley resembled those of He+ and H+ band waves, respectively, at GOES-13. The relatively few wave events at Halley with f > 1.0 Hz occurred at all local times, but with a modest, broad peak near dawn. Roughly 90% of both the 1570 Halley events < 1.0 Hz and the 142 Halley events > 1.0 Hz occurred during late storm recovery and quiet conditions. Events during compressions at GOES-13 (10%), Halley (6%), and RBSP A (6%) peaked near local noon, but with a secondary peak near midnight. Waves observed by RBSP A were distributed rather evenly in local time in all L shell ranges between 3 and 6, and the percentage occurring during late storm recovery or quiet conditions was only 65%. We interpret the difference in

  9. Forecasting the Radiation Belts for Satellites Undergoing Electric-Orbit Raising

    NASA Astrophysics Data System (ADS)

    Horne, R. B.; Glauert, S. A.; Meredith, N. P.; Kersten, T.; Heynderickx, D.; Maget, V.; Li, W.; Pitchford, D. A.; Wade, D.

    2015-12-01

    The introduction of commercial satellites with all-electric propulsion systems is nothing less than a revolution in the quest for low-cost access to space. As a consequence, it can take as long as 200 - 400 days to raise the perigee of the satellite to final geostationary orbit. During this time the satellites are exposed to the most intense part of the van Allen radiation belts where the electron radiation environment can vary by orders of magnitude as a result of changes in the solar wind. Here we describe briefly this new method of launch and discuss the importance of radiation protection, the need for real-time data on orbit and how physics based models can help supply this need. We describe the forecasting system that was developed in the European SPACECAST project, and is now continued in the SPACESTORM project, and how we use physics based models to forecast the electron flux throughout the outer radiation belt in real-time, updated hourly. We show that forecasts are much improved when the physics of wave-particle interactions is included, and show comparisons between models using different wave models for plasmaspheric hiss and chorus waves. The results emphasise the importance of chorus wave amplitudes. Finally, we discuss some areas of research needed to improve the forecasts, such as the need to understand electron flux drop-outs and their relation to distortions of the geomagnetic field in the tail region, and the need for additional wave models.

  10. Structure and evolution of electron "zebra stripes" in the inner radiation belt

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Zong, Q.-G.; Zhou, X.-Z.; Foster, J. C.; Rankin, R.

    2016-05-01

    "Zebra stripes" are newly found energetic electron energy-spatial (L shell) distributed structure with an energy between tens to a few hundreds keV in the inner radiation belt. Using high-quality measurements of electron fluxes from Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) on board the twin Van Allen Probes, we carry out case and statistical studies from April 2013 to April 2014 to study the structural and evolutionary characteristics of zebra stripes below L = 3. It is revealed that the zebra stripes can be transformed into evenly spaced patterns in the electron drift frequency coordinate: the detrended logarithmic fluxes in each L shell region can be well described by sinusoidal functions of drift frequency. The "wave number" of this sinusoidal function, which corresponds to the reciprocal of the gap between two adjacent peaks in the drift frequency coordinate, increases in proportion to real time. Further, these structural and evolutionary characteristics of zebra stripes can be reproduced by an analytic model of the evolution of the particle distribution under a single monochromatic or static azimuthal electric field. It is shown that the essential ingredient for the formation of multiple zebra stripes is the periodic drift of particles. The amplitude of the zebra stripes shows a good positive correlation with Kp index, which indicates that the generation mechanism of zebra stripes should be related to geomagnetic activities.

  11. 30 CFR 57.4503 - Conveyor belt slippage.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... drive pulley if slippage could cause ignition of the belt. (c) A person shall attend the belt at the... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Conveyor belt slippage. 57.4503 Section 57.4503... Control Installation/construction/maintenance § 57.4503 Conveyor belt slippage. (a) Surface belt...

  12. 30 CFR 57.4503 - Conveyor belt slippage.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... drive pulley if slippage could cause ignition of the belt. (c) A person shall attend the belt at the... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Conveyor belt slippage. 57.4503 Section 57.4503... Control Installation/construction/maintenance § 57.4503 Conveyor belt slippage. (a) Surface belt...

  13. Characteristics of pitch angle distributions of hundreds of keV electrons in the slot region and inner radiation belt

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Blake, J. B.; Fennell, J. F.; Claudepierre, S. G.; Baker, D. N.; Jaynes, A. N.; Malaspina, D. M.

    2014-12-01

    The pitch angle distribution (PAD) of energetic electrons in the slot region and inner radiation belt received little attention in the past decades due to the lack of quality measurements. Using the state-of-the-art pitch angle-resolved data from the Magnetic Electron Ion Spectrometer instrument onboard the Van Allen Probes, a detailed analysis of hundreds of keV electron PADs below L = 4 is performed, in which the PADs are categorized into three types: normal (flux peaking at 90°), cap (exceedingly peaking narrowly around 90°), and 90° minimum (lower flux at 90°) PADs. By examining the characteristics of the PADs of ˜460 keV electrons for over a year, we find that the 90° minimum PADs are generally present in the inner belt (L<2), while normal PADs dominate at L˜3.5-4. In the region between, 90° minimum PADs dominate during injection times and normal PADs dominate during quiet times. Cap PADs appear mostly at the decay phase of storms in the slot region and are likely caused by the pitch angle scattering of hiss waves. Fitting the normal PADs into sinnα form, the parameter n is much higher below L = 3 than that in the outer belt and relatively constant in the inner belt but changes significantly in the slot region (2 < L < 3) during injection times. As for the 90° minimum PADs, by performing a detailed case study, we find in the slot region this type of PAD is likely caused by chorus wave heating, but this mechanism can hardly explain the formation of 90° minimum PADs at the center of inner belt.

  14. Workshop on Techtonic Evolution of Greenstone Belts

    NASA Technical Reports Server (NTRS)

    Dewit, M. J. (Editor); Ashwal, Lewis D. (Editor)

    1986-01-01

    Topics addressed include: greenstone belt externalities; boundaries; rock terranes; synthesis and destiny; tectonic evolution; rock components and structure; sedimentology; stratigraphy; volcanism; metamorphism; and geophysics.

  15. Investigation of Moving Belt Radiator Technology Issues

    NASA Technical Reports Server (NTRS)

    Teagan, W. Peter; Aguilar, Jerry L.

    1994-01-01

    The development of an advanced spacecraft radiator technology is reported. The moving belt radiator is a thermal radiator concept with the promise of lower specific mass (per kW rejected) than that afforded by existing technologies. The results of a parametric study to estimate radiator mass for future space power systems is presented. It is shown that this technology can be scaled up to 200 MW for higher rejection temperatures. Several aspects of the design concept are discussed, including the dynamics of a large rotating belt in microgravity. The results of a computer code developed to model the belt dynamics are presented. A series of one-g experiments to investigate the dynamics of small belts is described. A comprehensive test program to investigate belt dynamics in microgravity aboard the NASA KC-135 aircraft is discussed. It was found that the desired circular shape can readily be achieved in microgravity. It is also shown that a rotating belt is stable when subjected to simulated attitude control maneuvers. Heat exchanger design is also investigated. Several sealing concepts were examined experimentally, and are discussed. Overall heat transfer coefficients to the rotating belt are presented. Material properties for various belt materials, including screen meshes, are also presented. The results presented in this report indicate that the moving belt radiator concept is technically feasible.

  16. Nuclear cascades in Saturn's rings - Cosmic ray albedo neutron decay and origins of trapped protons in the inner magnetosphere

    NASA Technical Reports Server (NTRS)

    Cooper, J. F.

    1983-01-01

    The nearly equatorial trajectory of the Pioneer 11 spacecraft through Saturn's high energy proton radiation belts and under the main A-B-C rings provided a unique opportunity to study the radial dependence of the greater than 30 MeV proton intensities in the belts in terms of models for secondary nucleon production by cosmic ray interactions in the rings, in situ proton injection in the radiation belts by neutron beta decay, magnetospheric diffusion, and absorption by planetary rings and satellites. Maximum trapped proton intensities measured by Pioneer 11 in the radiation belts are compared with calculated intensities and found consistent with trapping times of roughly 40 years and a radial diffusion coefficient of about 10 to the -15th L to the 9th R sub s squared/s. Differential energy spectra proportional to E to the -2 estimated from integral measurements of trapped photons with E greater than 100 MeV are consistent with the beta decay model, but an inferred turndown of the spectra toward lower energies and reported integral proton anisotropies of a specified form both indicate the need for more realistic calculations of the neutron source from the rings and the radiation belt loss processes.

  17. Nuclear cascades in Saturn's rings - Cosmic ray albedo neutron decay and origins of trapped protons in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.

    1983-05-01

    The nearly equatorial trajectory of the Pioneer 11 spacecraft through Saturn's high energy proton radiation belts and under the main A-B-C rings provided a unique opportunity to study the radial dependence of the greater than 30 MeV proton intensities in the belts in terms of models for secondary nucleon production by cosmic ray interactions in the rings, in situ proton injection in the radiation belts by neutron beta decay, magnetospheric diffusion, and absorption by planetary rings and satellites. Maximum trapped proton intensities measured by Pioneer 11 in the radiation belts are compared with calculated intensities and found consistent with trapping times of roughly 40 years and a radial diffusion coefficient of about 10 to the -15th L to the 9th Rs squared/s. Differential energy spectra proportional to E to the -2 estimated from integral measurements of trapped photons with E greater than 100 MeV are consistent with the beta decay model, but an inferred turndown of the spectra toward lower energies and reported integral proton anisotropies of a specified form both indicate the need for more realistic calculations of the neutron source from the rings and the radiation belt loss processes.

  18. Highly Relativistic Radiation Belt Electron Acceleration, Transport, and Loss: Large Solar Storm Events of March and June 2015

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Jaynes, A. N.; Kanekal, S. G.; Foster, J.C.; Erickson, P. J.; Fennell, Joseph; Blake, J. B.; Zhao, H.; Li, X.; Elkington, S. R.; Henderson, M. G.; Reeves, G.; Spence, H.; Kletzing, C. A.; Wygant, J. R.

    2016-01-01

    Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (Disturbance Storm Time Ring Current Index) value reaching 223 nanoteslas. On 22 June 2015 another strong storm (Dst reaching 204 nanoteslas) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E (Energy) greater than or approximately equal to 1 millielectronvolt) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 millielectronvolts in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong butterfly distributions with deep minima in flux at alpha equals 90 degrees. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported impenetrable barrier at L (L-shell magnetic field line value) approximately equal to 2.8 was pushed inward, but not significantly breached, and no E (Energy) greater than or approximately equal to 2.0 millielectronvolts electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Overall, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.

  19. Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015

    DOE PAGES

    Baker, Daniel N.; Jaynes, A. N.; Kanekal, S. G.; ...

    2016-07-01

    Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching –223 nT. On 22 June 2015 another strong storm (Dst reaching –204 nT) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed amore » rich variety of pitch angle features including strong “butterfly” distributions with deep minima in flux at α = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported “impenetrable barrier” at L ≈ 2.8 was pushed inward, but not significantly breached, and no E ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Altogether, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.« less

  20. Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015

    PubMed Central

    Jaynes, A. N.; Kanekal, S. G.; Foster, J. C.; Erickson, P. J.; Fennell, J. F.; Blake, J. B.; Zhao, H.; Li, X.; Elkington, S. R.; Henderson, M. G.; Reeves, G. D.; Spence, H. E.; Kletzing, C. A.; Wygant, J. R.

    2016-01-01

    Abstract Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection‐driven event occurred with a Dst (storm time ring current index) value reaching −223 nT. On 22 June 2015 another strong storm (Dst reaching −204 nT) was recorded. These two storms each produced almost total loss of radiation belt high‐energy (E ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong “butterfly” distributions with deep minima in flux at α = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported “impenetrable barrier” at L ≈ 2.8 was pushed inward, but not significantly breached, and no E ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Overall, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis. PMID:27867796

  1. Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015

    SciTech Connect

    Baker, Daniel N.; Jaynes, A. N.; Kanekal, S. G.; Foster, J. C.; Erickson, P. J.; Fennell, J. F.; Blake, J. B.; Zhao, H.; Li, X.; Elkington, S. R.; Henderson, Michael Gerard; Reeves, G. D.; Spence, H. E.; Kletzing, C. A.; Wygant, J. R.

    2016-07-01

    Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching –223 nT. On 22 June 2015 another strong storm (Dst reaching –204 nT) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong “butterfly” distributions with deep minima in flux at α = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported “impenetrable barrier” at L ≈ 2.8 was pushed inward, but not significantly breached, and no E ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Altogether, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.

  2. Effects of ULF wave power on relativistic radiation belt electrons: 8-9 October 2012 geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Pokhotelov, D.; Rae, I. J.; Murphy, K. R.; Mann, I. R.

    2016-12-01

    Electromagnetic ultralow-frequency (ULF) waves are known to play a substantial role in radial transport, acceleration, and loss of relativistic particles trapped in the Earth's outer radiation belt. Using in situ observations by multiple spacecraft operating in the vicinity of outer radiation belts, we analyze the temporal and spatial behavior of ULF waves throughout the geomagnetic storm of 8-9 October 2012 and compare with the dynamics of relativistic electron fluxes on board the twin Van Allen Probes spacecraft. The analysis shows that the relativistic electron fluxes reduce from their prestorm levels during the first phase of the storm and rapidly increase during the second phase of the storm. We demonstrate that the behavior of ULF wave power changes throughout the storm, from ULF oscillations being a mixture of compressional and shear magnetic components during the first phase of the storm to ULF oscillations being dominated by transverse (shear) components during the second phase. We analyze the parameters of ULF-driven radial diffusion throughout the storm and compare the observed diffusion coefficients with their statistical averages. We demonstrate that the observed diffusion coefficients are strong enough to impact the redistribution of relativistic electron fluxes from and to the outer boundary of radiation belts and the diffusion might influence the effects of any local electron acceleration by transporting fluxes inward or outward according to phase space density gradients.

  3. Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015.

    PubMed

    Baker, D N; Jaynes, A N; Kanekal, S G; Foster, J C; Erickson, P J; Fennell, J F; Blake, J B; Zhao, H; Li, X; Elkington, S R; Henderson, M G; Reeves, G D; Spence, H E; Kletzing, C A; Wygant, J R

    2016-07-01

    Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching -223 nT. On 22 June 2015 another strong storm (Dst reaching -204 nT) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong "butterfly" distributions with deep minima in flux at α = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported "impenetrable barrier" at L ≈ 2.8 was pushed inward, but not significantly breached, and no E ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Overall, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.

  4. Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015

    NASA Astrophysics Data System (ADS)

    Baker, D. N.; Jaynes, A. N.; Kanekal, S. G.; Foster, J. C.; Erickson, P. J.; Fennell, J. F.; Blake, J. B.; Zhao, H.; Li, X.; Elkington, S. R.; Henderson, M. G.; Reeves, G. D.; Spence, H. E.; Kletzing, C. A.; Wygant, J. R.

    2016-07-01

    Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching -223 nT. On 22 June 2015 another strong storm (Dst reaching -204 nT) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong "butterfly" distributions with deep minima in flux at α = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported "impenetrable barrier" at L ≈ 2.8 was pushed inward, but not significantly breached, and no E ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Overall, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.

  5. Cognition About the Creative Process – Interview With Dr Andrew P. Allen

    PubMed Central

    Allen, Andrew P.; Loughnane, Lynda

    2016-01-01

    What is the relationship between the creative process and cognition and perception? Lynda Loughnane, a master’s student in Art and Process in Crawford College of Art and Design, Cork, Ireland interviewed Dr Andrew P. Allen about the subject. Areas covered include mindfulness, Type 1 and Type 2 thinking, stage theories of creativity, engagement with the art process and the artwork, phenomenology and consciousness with and without self report. The interview was constructed to cover a wide range of subject matter, so as to gather as much information as possible in layman's language about the cognitive process in relation to creativity and interaction with art. PMID:27872674

  6. Evaluation of Single Board Computers for the Antenna Controller at the Allen Telescope Array

    NASA Astrophysics Data System (ADS)

    Harp, Gerald R.

    2002-12-01

    We review a variety off-the-shelf single board computers being considered for application in the Allen Telescope Array (ATA) for antenna control. The evaluation process used the following procedure: we developed an equivalent small program on each computer. This program communicates over a local area network (Ethernet) to a remote host, and makes some simple tests of the network bandwidth. The controllers are evaluated according to 1) the measured performance and 2) the time it takes to develop the software. Based on these tests we rate each controller and choose one based on the Ajile aJ-100 processor for application at the ATA.

  7. Evaluation of effects of groundwater withdrawals at the proposed Allen combined-cycle combustion turbine plant, Shelby County, Tennessee

    USGS Publications Warehouse

    Haugh, Connor J.

    2016-08-10

    The Mississippi Embayment Regional Aquifer Study groundwater-flow model was used to simulate the potential effects of future groundwater withdrawals at the proposed Allen combined-cycle combustion turbine plant in Shelby County, Tennessee. The scenario used in the simulation consisted of a 30-year average withdrawal period followed by a 30-day maximum withdrawal period. Effects of withdrawals at the Allen plant site on the Mississippi embayment aquifer system were evaluated by comparing the difference in simulated water levels in the aquifers at the end of the 30-year average withdrawal period and at the end of the scenario to a base case without the Allen combined-cycle combustion turbine plant withdrawals. Simulated potentiometric surface declines in the Memphis aquifer at the Allen plant site were about 7 feet at the end of the 30-year average withdrawal period and 11 feet at the end of the scenario. The affected area of the Memphis aquifer at the Allen plant site as delineated by the 4-foot potentiometric surface-decline contour was 2,590 acres at the end of the 30-year average withdrawal period and 11,380 acres at the end of the scenario. Simulated declines in the underlying Fort Pillow aquifer and overlying shallow aquifer were both less than 1 foot at the end of the 30-year average withdrawal period and the end of the scenario.

  8. 47. INTERIOR VIEW, DETAIL OF CONVEYOR BELT SYSTEM SYSTEM WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    47. INTERIOR VIEW, DETAIL OF CONVEYOR BELT SYSTEM SYSTEM WITH BACK BELT DROPPING HARDENED NAILS ON THE FRONT BELT TO BE TEMPERED; MOTION STOPPED - LaBelle Iron Works, Thirtieth & Wood Streets, Wheeling, Ohio County, WV

  9. Jupiter's radiation belts and atmosphere

    NASA Technical Reports Server (NTRS)

    De Pater, I.; Dames, H. A. C.

    1979-01-01

    Maps and stripscans of the radio emission from Jupiter were made during the Pioneer 10 flyby in December 1973 at wavelengths of 6 cm, 21 cm, and 50 cm using the Westerbork telescope in the Netherlands. With this instrument the disk of the planet was resolved at 6 and 21 cm. The pictures are averaged over 15 deg of Jovian longitude. At 21 cm the stripscans clearly show the existence of a 'hot region' in the radiation belts at a System III longitude (1965.0) of 255 + or - 10 deg. Its flux is about 9% of the total nonthermal flux, and it has a volume emissivity enhanced by a factor of about 1.6 with respect to the general radiation belts. The temperature of the thermal disk at 21 cm appears to be 290 + or - 20 K. This is likely due to a high ammonia mixing ratio in the atmosphere, a factor of 4-5 larger than the expected solar value of 0.00015.

  10. Beyond the Kuiper Belt Edge

    NASA Astrophysics Data System (ADS)

    Sheppard, Scott

    2013-01-01

    Of the thousands of known objects beyond Neptune, only one has a perihelion significantly beyond 50 AU, Sedna at 75 AU. Most Kuiper Belt surveys to date either did not go faint enough, did not have the required long cadence to detect very slow moving objects or covered too small of an area of sky to efficiently detect objects beyond 50 AU. The dynamical and physical properties of objects in this region offer key constraints on the formation and evolution of our solar system. In order to probe the Sedna like population of objects with moderate radii (100 km) we are conducting a deep wide-field outer solar system survey. This survey will allow us to determine if the objects beyond 50 AU are fainter than expected, if there is truly a dearth of objects, or if the Kuiper Belt continues again after some sizable gap possibly caused by a planet sized object. We will be able to examine the origin of Sedna and determine if it is unique (as once believed for Pluto) or one of a new class of object. We request one night in 2013B to recover a very interesting object that we discovered at Subaru in July 2012 and complete the sky coverage needed to constrain the Sedna-like population. This one night was awarded to us in 2012B but lost because of instrument problems.

  11. Beyond the Kuiper Belt Edge

    NASA Astrophysics Data System (ADS)

    Sheppard, Scott

    2012-01-01

    Of the thousands of known objects beyond Neptune, only one has a perihelion significantly beyond 50 AU, Sedna at 75 AU. Most Kuiper Belt surveys to date either did not go faint enough, did not have the required long cadence to detect very slow moving objects or covered too small of an area of sky to efficiently detect objects beyond 50 AU. The dynamical and physical properties of objects in this region offer key constraints on the formation and evolution of our solar system. In order to probe the Sedna like population of objects with moderate radii (100 km) we are conducting a deep wide-field outer solar system survey. This survey will allow us to determine if the objects beyond 50 AU are fainter than expected, if there is truly a dearth of objects, or if the Kuiper Belt continues again after some sizable gap possibly caused by a planet sized object. We will be able to examine the origin of Sedna and determine if it is unique (as once believed for Pluto) or one of a new class of object. We request one night in 2012B to recover interesting objects that will be discovered at Subaru in July 2012 and complete the sky coverage needed to constrain the Sedna-like population.

  12. 14 CFR 27.1413 - Safety belts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Safety belts. 27.1413 Section 27.1413 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1413 Safety belts. Each safety...

  13. 36 CFR 1004.15 - Safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Safety belts. 1004.15 Section 1004.15 Parks, Forests, and Public Property PRESIDIO TRUST VEHICLES AND TRAFFIC SAFETY § 1004.15 Safety... administered by the Presidio Trust will have the safety belt or child restraint system properly fastened at...

  14. 14 CFR 27.1413 - Safety belts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Safety belts. 27.1413 Section 27.1413 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1413 Safety belts. Each safety...

  15. 36 CFR 1004.15 - Safety belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Safety belts. 1004.15 Section 1004.15 Parks, Forests, and Public Property PRESIDIO TRUST VEHICLES AND TRAFFIC SAFETY § 1004.15 Safety... administered by the Presidio Trust will have the safety belt or child restraint system properly fastened at...

  16. 14 CFR 27.1413 - Safety belts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Safety belts. 27.1413 Section 27.1413 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1413 Safety belts. Each safety...

  17. 36 CFR 1004.15 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Safety belts. 1004.15 Section 1004.15 Parks, Forests, and Public Property PRESIDIO TRUST VEHICLES AND TRAFFIC SAFETY § 1004.15 Safety... administered by the Presidio Trust will have the safety belt or child restraint system properly fastened at...

  18. 36 CFR 1004.15 - Safety belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Safety belts. 1004.15 Section 1004.15 Parks, Forests, and Public Property PRESIDIO TRUST VEHICLES AND TRAFFIC SAFETY § 1004.15 Safety... administered by the Presidio Trust will have the safety belt or child restraint system properly fastened at...

  19. 14 CFR 27.1413 - Safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Safety belts. 27.1413 Section 27.1413 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1413 Safety belts. Each safety...

  20. 36 CFR 1004.15 - Safety belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Safety belts. 1004.15 Section 1004.15 Parks, Forests, and Public Property PRESIDIO TRUST VEHICLES AND TRAFFIC SAFETY § 1004.15 Safety... administered by the Presidio Trust will have the safety belt or child restraint system properly fastened at...