111 results on '"J. H. Clemmons"'
Search Results
2. A Revised Look at Relativistic Electrons in the Earth's Inner Radiation Zone and Slot Region
- Author
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S. G. Claudepierre, T. P. O'Brien, M. D. Looper, J. B. Blake, J. F. Fennell, J. L. Roeder, J. H. Clemmons, J. E. Mazur, D. L. Turner, G. D. Reeves, and H. E. Spence
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- 2019
- Full Text
- View/download PDF
3. Observations of Spatial Variations in O/N2 During an Auroral Substorm Using the Multichannel Downlooking Camera on the VISIONS Rocket
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J. H. Hecht, J. H. Clemmons, M. G. Conde, D. L. Hampton, R. G. Michell, D. E. Rowland, R. F. Pfaff, and R. L. Walterscheid
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- 2018
- Full Text
- View/download PDF
4. The hidden dynamics of relativistic electrons (0.7–1.5 MeV) in the inner zone and slot region
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S. G. Claudepierre, T. P. O'Brien, J. F. Fennell, J. B. Blake, J. H. Clemmons, M. D. Looper, J. E. Mazur, J. L. Roeder, D. L. Turner, G. D. Reeves, and H. E. Spence
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- 2017
- Full Text
- View/download PDF
5. Energy limits of electron acceleration in the plasma sheet during substorms: A case study with the Magnetospheric Multiscale (MMS) mission
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D. L. Turner, J. F. Fennell, J. B. Blake, J. H. Clemmons, B. H. Mauk, I. J. Cohen, A. N. Jaynes, J. V. Craft, F. D. Wilder, D. N. Baker, G. D. Reeves, D. J. Gershman, L. A. Avanov, J. C. Dorelli, B. L. Giles, C. J. Pollock, D. Schmid, R. Nakamura, R. J. Strangeway, C. T. Russell, A. V. Artemyev, A. Runov, V. Angelopoulos, H. E. Spence, R. B. Torbert, and J. L. Burch
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- 2016
- Full Text
- View/download PDF
6. Microinjections observed by MMS FEEPS in the dusk to midnight region
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J. F. Fennell, D. L. Turner, C. L. Lemon, J. B. Blake, J. H. Clemmons, B. H. Mauk, A. N. Jaynes, I. J. Cohen, J. H. Westlake, D. N. Baker, J. V. Craft, H. E. Spence, G. D. Reeves, R. B. Torbert, J. L. Burch, B. L. Giles, W. R. Paterson, and R. J. Strangeway
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- 2016
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- View/download PDF
7. Observations of energetic particle escape at the magnetopause: Early results from the MMS Energetic Ion Spectrometer (EIS)
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I. J. Cohen, B. H. Mauk, B. J. Anderson, J. H. Westlake, D. G. Sibeck, B. L. Giles, C. J. Pollock, D. L. Turner, J. F. Fennell, J. B. Blake, J. H. Clemmons, A. N. Jaynes, D. N. Baker, J. V. Craft, H. E. Spence, J. T. Niehof, G. D. Reeves, R. B. Torbert, C. T. Russell, R. J. Strangeway, W. Magnes, K. J. Trattner, S. A. Fuselier, and J. L. Burch
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- 2016
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- View/download PDF
8. Multipoint Observations of Energetic Particle Injections and Substorm Activity During a Conjunction Between Magnetospheric Multiscale (MMS) and Van Allen Probes
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D. L. Turner, J. F. Fennell, J. B. Blake, S. G. Claudepierre, J. H. Clemmons, A. N. Jaynes, T. Leonard, D. N. Baker, I. J. Cohen, M. Gkioulidou, A. Y. Ukhorskiy, B. H. Mauk, C. Gabrielse, V. Angelopoulos, R. J. Strangeway, C. A. Kletzing, O. Le Contel, H. E. Spence, R. B. Torbert, J. L. Burch, and G. D. Reeves
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- 2017
- Full Text
- View/download PDF
9. A background correction algorithm for Van Allen Probes MagEIS electron flux measurements
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S. G. Claudepierre, T. P. O'Brien, J. B. Blake, J. F. Fennell, J. L. Roeder, J. H. Clemmons, M. D. Looper, J. E. Mazur, T. M. Mulligan, H. E. Spence, G. D. Reeves, R. H. W. Friedel, M. G. Henderson, and B. A. Larsen
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- 2015
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10. Van Allen Probes observations of direct wave‐particle interactions
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J. F. Fennell, J. L. Roeder, W. S. Kurth, M. G. Henderson, B. A. Larsen, G. Hospodarsky, J. R. Wygant, J. S. G. Claudepierre, J. B. Blake, H. E. Spence, J. H. Clemmons, H. O. Funsten, C. A. Kletzing, and G. D. Reeves
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- 2014
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11. The Magnetic Electron Ion Spectrometer: A Review of On-Orbit Sensor Performance, Data, Operations, and Science
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Drew Turner, M. D. Looper, James L. Roeder, J. H. Clemmons, A. J. Boyd, Geoff Reeves, J. B. Blake, Christine Gabrielse, Seth G. Claudepierre, T. P. O'Brien, J. E. Mazur, J. F. Fennell, and Harlan E. Spence
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Energetic magnetospheric particles ,Spectrometer ,Computer science ,business.industry ,Astronomy and Astrophysics ,Electron ,Radiation ,Charged particle ,Article ,symbols.namesake ,Particle instrument operation ,Space and Planetary Science ,Van Allen radiation belt ,Orbit (dynamics) ,symbols ,Van Allen Probes ,Relativistic electron sensors ,Instrumentation (computer programming) ,Aerospace engineering ,business ,Acceleration, transport, and loss of radiation belt particles - Abstract
Measurements from NASA's Van Allen Probes have transformed our understanding of the dynamics of Earth's geomagnetically-trapped, charged particle radiation. The Van Allen Probes were equipped with the Magnetic Electron Ion Spectrometers (MagEIS) that measured energetic and relativistic electrons, along with energetic ions, in the radiation belts. Accurate and routine measurement of these particles was of fundamental importance towards achieving the scientific goals of the mission. We provide a comprehensive review of the MagEIS suite's on-orbit performance, operation, and data products, along with a summary of scientific results. The purpose of this review is to serve as a complement to the MagEIS instrument paper, which was largely completed before flight and thus focused on pre-flight design and performance characteristics. As is the case with all space-borne instrumentation, the anticipated sensor performance was found to be different once on orbit. Our intention is to provide sufficient detail on the MagEIS instruments so that future generations of researchers can understand the subtleties of the sensors, profit from these unique measurements, and continue to unlock the mysteries of the near-Earth space radiation environment. Supplementary Information The online version contains supplementary material available at 10.1007/s11214-021-00855-2.
- Published
- 2021
12. A Revised Look at Relativistic Electrons in the Earth's Inner Radiation Zone and Slot Region
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Harlan E. Spence, J. F. Fennell, T. P. O'Brien, James L. Roeder, M. D. Looper, Geoffrey D. Reeves, J. B. Blake, Seth G. Claudepierre, Drew Turner, J. E. Mazur, and J. H. Clemmons
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010504 meteorology & atmospheric sciences ,Proton ,Magnetosphere: Inner ,Radiation Belts ,Electron ,radiation belt ,Space weather ,01 natural sciences ,symbols.namesake ,Energetic Particles: Trapped ,Magnetospheric Physics ,Van Allen Probes ,Instruments and Techniques ,Space Radiation Environment ,Research Articles ,slot region ,0105 earth and related environmental sciences ,Physics ,inner zone ,Spectrometer ,Particle Dynamics in the Earth's Radiation Belts ,particle detectors ,Radiation zone ,relativistic electrons ,Computational physics ,Geophysics ,Space and Planetary Science ,Van Allen radiation belt ,symbols ,Space Weather ,Interplanetary spaceflight ,Research Article - Abstract
We describe a new, more accurate procedure for estimating and removing inner zone background contamination from Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS) radiation belt measurements. This new procedure is based on the underlying assumption that the primary source of background contamination in the electron measurements at L shells less than three, energetic inner belt protons, is relatively stable. Since a magnetic spectrometer can readily distinguish between foreground electrons and background signals, we are able to exploit the proton stability to construct a model of the background contamination in each MagEIS detector by only considering times when the measurements are known to be background dominated. We demonstrate, for relativistic electron measurements in the inner zone, that the new technique is a significant improvement upon the routine background corrections that are used in the standard MagEIS data processing, which can “overcorrect” and therefore remove real (but small) electron fluxes. As an example, we show that the previously reported 1‐MeV injection into the inner zone that occurred in June of 2015 was distributed more broadly in L and persisted in the inner zone longer than suggested by previous estimates. Such differences can have important implications for both scientific studies and spacecraft engineering applications that make use of MagEIS electron data in the inner zone at relativistic energies. We compare these new results with prior work and present more recent observations that also show a 1‐MeV electron injection into the inner zone following the September 2017 interplanetary shock passage., Key Points A new background correction algorithm for relativistic inner zone electrons is developedWe find important differences versus the standard algorithm, with several new/clarified features revealedData from the new algorithm should be used for quantitative inner zone studies at energies >0.7 MeV
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- 2019
13. RENU2 UV PMT Observations of the Cusp
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D. R. Kenward, James H. Hecht, Stanley C. Solomon, Kenneth F. Dymond, J. H. Clemmons, Timothy A. Cook, Kristina A. Lynch, B. Fritz, Supriya Chakrabarti, and Marc Lessard
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Physics ,010504 meteorology & atmospheric sciences ,Astrophysics ,medicine.disease_cause ,01 natural sciences ,010309 optics ,Geophysics ,0103 physical sciences ,medicine ,General Earth and Planetary Sciences ,Cusp (anatomy) ,Ionosphere ,Ultraviolet ,0105 earth and related environmental sciences - Published
- 2020
14. A New Technique for Estimating the Lifetime of Bursts of Electron Precipitation From Sounding Rocket Measurements
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J. S. Evans, D. L. Kenward, F. B. Sadler, James H. Hecht, Marc Lessard, Kristina A. Lynch, B. Fritz, and J. H. Clemmons
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Physics ,Geophysics ,Sounding rocket ,General Earth and Planetary Sciences ,Electron precipitation - Published
- 2020
15. RENU2 Rocket Observations of Fine-Scale Thermal Ion Upflow, Downflow, and Temperature
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D. R. Kenward, J. H. Clemmons, M. I. Harrington, David L. Hysell, Lasse Boy Novock Clausen, Fred Sigernes, Moen Idar Jøran, M. Burleigh, Kristina A. Lynch, Matthew D. Zettergren, N. H. Godbole, Thomas Maximillian Roberts, P. A. Fernandes, Kjellmar Oksavik, B. Fritz, and Marc Lessard
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Sounding rocket ,business.product_category ,Materials science ,Rocket ,Scale (ratio) ,Field (physics) ,Physics::Plasma Physics ,Physics::Space Physics ,Thermal ,Ion temperature ,business ,Ion ,Computational physics - Abstract
We present an analysis of in-situ thermal ion measurements from a cusp auroral sounding rocket. Using a forward modeling procedure, we find most-probable thermal ion temperature and parallel (field...
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- 2020
16. Daytime Dynamo Electrodynamics With Spiral Currents Driven by Strong Winds Revealed by Vapor Trails and Sounding Rocket Probes
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Jeffrey Klenzing, Tatsuhiro Yokoyama, Neil Murphy, Masa-yuki Yamamoto, Terence Bullett, Y. Kakinami, Rebecca Bishop, Justin Mabie, Shigeto Watanabe, J. H. Clemmons, Y. Yamazaki, Miguel Larsen, Takumi Abe, Mamoru Yamamoto, Douglas E. Rowland, Henry Freudenreich, R. F. Pfaff, Vassilis Angelopoulos, Hiroto Habu, and Richard L. Walterscheid
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Daytime ,business.product_category ,010504 meteorology & atmospheric sciences ,Electric Fields ,Atmospheric Composition and Structure ,010502 geochemistry & geophysics ,01 natural sciences ,Thermosphere: Energy Deposition ,Midlatitude Ionosphere ,Physics::Geophysics ,Electric field ,Research Letter ,Meteorology & Atmospheric Sciences ,Atmospheric dynamo ,Astrophysics::Solar and Stellar Astrophysics ,Magnetospheric Physics ,Ionosphere ,Physics::Atmospheric and Oceanic Physics ,Current Systems ,0105 earth and related environmental sciences ,Physics ,Sounding rocket ,Thermospheric Dynamics ,Geophysics ,Field‐aligned Currents and Current Systems ,Research Letters ,Magnetic field ,Rocket ,Physics::Space Physics ,Atmospheric Processes ,General Earth and Planetary Sciences ,Ionospheric Dynamics ,business ,Current density ,Space Sciences ,Dynamo - Abstract
We investigate the forces and atmosphere‐ionosphere coupling that create atmospheric dynamo currents using two rockets launched nearly simultaneously on 4 July 2013 from Wallops Island (USA), during daytime Sq conditions with ΔH of −30 nT. One rocket released a vapor trail observed from an airplane which showed peak velocities of >160 m/s near 108 km and turbulence coincident with strong unstable shear. Electric and magnetic fields and plasma density were measured on a second rocket. The current density peaked near 110 km exhibiting a spiral pattern with altitude that mirrored that of the winds, suggesting the dynamo is driven by tidal forcing. Such stratified currents are obscured in integrated ground measurements. Large electric fields produced a current opposite to that driven by the wind, believed created to minimize the current divergence. Using the observations, we solve the dynamo equation versus altitude, providing a new perspective on the complex nature of the atmospheric dynamo., Key Points Comprehensive observations of the daytime Sq dynamo electrodynamics have been gathered for the first timeObserved daytime winds in the dynamo region are much larger than expected yet their currents are reduced by those of DC electric fieldsWinds and currents exhibit an interleaved spiral pattern indicative of tidal forcing
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- 2020
17. 'Endurance', a new NASA mission to gauge Earth’s polar wind ambipolar electric field
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David L. Mitchell, Mark Lester, Suzanne M. Imber, Robert Michell, Scott Bissett, Max King, Aroh Barjatya, J. H. Clemmons, Robert F. Pfaff, Frank Eparvier, Alex Glocer, and Glyn Collinson
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Physics ,Polar wind ,Ambipolar diffusion ,Electric field ,Quantum electrodynamics ,Gauge (firearms) ,Earth (classical element) - Abstract
Earth’s primary ionospheric loss process is the polar wind, which flows outwards along open magnetic field lines above our polar caps. One key component critical to the formation of this outflow is thought to be a weak ambipolar electric field. The potential drop resulting from this electric field is thought to assist terrestrial atmospheric escape since it reduces the potential barrier required for heavier ions (such as O+) to escape and accelerates light ions (such as H+) to escape velocity. Although a key component to atmospheric loss, Earth’s ambipolar electric field has never been measured due to its weak strength. We announce the NASA Endurance mission, launching in 2022, which will attempt to make the first direct in-situ observations of Earth’s ambipolar electric field. Endurance launch from Ny-Ålesund, Svalbard, and soar across the exobase to altitudes greater than 800km. The spacecraft will be equipped with a new type of scientific instrument which will enable the Endurance to measure the total electric potential drop below her. She will also be equipped with a full array of sensors that will enable the science team to self-consistently model the polar wind during the flight to test our current theoretical understanding of the physical processes which generate Earth’s ambipolar electric field.Endurance will perform groundbreaking discovery science, measuring a fundamental property of Earth for the first time: the strength of the ambipolar electric field generated by its ionosphere. The results will provide us with a better understanding of atmospheric escape at Earth, and why our planet is habitable.
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- 2020
18. Overview of the Rocket Experiment for NeutralUpwelling Sounding Rocket 2 (RENU2)
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Ian J. Cohen, T.M. Roberts, Kjellmar Oksavik, D. R. Kenward, Kristina A. Lynch, James H. Hecht, Geoff Crowley, M. I. Harrington, Marc Lessard, Lasse Boy Novock Clausen, N. H. Godbole, Joran Moen, Tim K. Yeoman, David L. Hysell, B. Sadler, Fred Sigernes, M. Syrjäsuo, Noora Partamies, J. H. Clemmons, Pål Gunnar Ellingsen, and B. Fritz
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Physics ,Geophysics ,business.product_category ,Sounding rocket ,Rocket ,business.industry ,General Earth and Planetary Sciences ,Upwelling ,Aerospace engineering ,business - Abstract
The Rocket Experiment for Neutral Upwelling 2 (RENU2) rocket was launched on 13 December 2015 at 07:34 UT. The payload transited the cusp region during a neutral upwelling event, supported by a comprehensive set of onboard and ground-based instrumentation. RENU2 data highlight two important processes. One is that a proper understanding of neutral upwelling by Poleward Moving Auroral Forms (PMAFs) requires a treatment that mimics the quasiperiodic passage of a sequence of PMAFs. As a PMAF reaches a flux tube, its physical consequences must be determined including the residual history of effects from previous passages, implying that understanding such a process requires an accounting of the system hysteresis. Second, RENU2 observations suggest that neutral density enhancements driven by precipitation and/or Joule heating can be highly structured in altitude and latitude. In addition, timescales involving neutral dynamics suggest that the structuring must be slowly changing, for example, over the course of 10 to tens of minutes. publishedVersion
- Published
- 2020
19. Observations of Spatial Variations in O/N 2 During an Auroral Substorm Using the Multichannel Downlooking Camera on the VISIONS Rocket
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Robert Michell, Mark Conde, Richard L. Walterscheid, Douglas E. Rowland, J. H. Clemmons, R. F. Pfaff, James H. Hecht, and Don L. Hampton
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Geophysics ,business.product_category ,010504 meteorology & atmospheric sciences ,Rocket ,Space and Planetary Science ,0103 physical sciences ,Substorm ,Environmental science ,business ,010303 astronomy & astrophysics ,01 natural sciences ,0105 earth and related environmental sciences - Published
- 2018
20. A multiyear (2002–2006) climatology of O/N2 in the lower thermosphere from TIMED GUVI and ground‐based photometer observations
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J. H. Hecht, T. Mulligan, J. T. Correira, J. H. Clemmons, D. J. Strickland, R. L. Walterscheid, and M. G. Conde
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- 2012
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21. Strong magnetic field fluctuations within filamentary auroral density cavities interpreted as VLF saucer sources
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D. J. Knudsen, R. Kabirzadeh, J. K. Burchill, R. F. Pfaff, D. D. Wallis, S. R. Bounds, J. H. Clemmons, and J.‐L. Pinçon
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- 2012
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22. The hidden dynamics of relativistic electrons (0.7–1.5 MeV) in the inner zone and slot region
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Drew Turner, James L. Roeder, M. D. Looper, J. E. Mazur, J. H. Clemmons, J. F. Fennell, J. B. Blake, Seth G. Claudepierre, T. P. O'Brien, Harlan E. Spence, and Geoffrey D. Reeves
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Geomagnetic storm ,Physics ,010504 meteorology & atmospheric sciences ,Flux ,Electron ,Space weather ,01 natural sciences ,Spectral line ,Ion ,symbols.namesake ,Geophysics ,Space and Planetary Science ,Van Allen radiation belt ,0103 physical sciences ,symbols ,Van Allen Probes ,Atomic physics ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences - Abstract
We present measurements of relativistic electrons (0.7–1.5 MeV) in the inner zone and slot region obtained by the Magnetic Electron and Ion Spectrometer (MagEIS) instrument on Van Allen Probes. The data presented are corrected for background contamination, which is primarily due to inner-belt protons in these low-L regions. We find that ∼1 MeV electrons were transported into the inner zone following the two largest geomagnetic storms of the Van Allen Probes era to date, the March and June 2015 events. As ∼1 MeV electrons were not observed in Van Allen Probes data in the inner zone prior to these two events, the injections created a new inner belt that persisted for at least 1.5 years. In contrast, we find that electrons injected into the slot region decay on much faster timescales, approximately tens of days. Furthermore, we find no evidence of >1.5 MeV electrons in the inner zone during the entire time interval considered (April 2013 through September 2016). The energies we examine thus span a transition range in the steeply falling inner zone electron spectrum, where modest intensities are observed at 0.7 MeV, and no electrons are observed at 1.5 MeV. To validate the results obtained from the background corrected flux measurements, we also present detailed pulse-height spectra from individual MagEIS detectors. These measurements confirm our results and also reveal low-intensity inner zone and slot region electrons that are not captured in the standard background corrected data product. Finally, we briefly discuss efforts to refine the upper limit of inner zone MeV electron flux obtained in earlier work.
- Published
- 2017
23. Current energetic particle sensors
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Shrikanth Kanekal, J. B. Blake, D. J. Mabry, Seth G. Claudepierre, J. F. Fennell, J. H. Clemmons, Daniel N. Baker, Paul O'Brien, J. E. Mazur, and W. R. Crain
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Physics ,010504 meteorology & atmospheric sciences ,Spectrometer ,business.industry ,Astrophysics::Instrumentation and Methods for Astrophysics ,Electron ,01 natural sciences ,Ion ,law.invention ,Telescope ,Proton (rocket family) ,Geophysics ,Space and Planetary Science ,law ,0103 physical sciences ,Orbit (dynamics) ,Van Allen Probes ,CubeSat ,Aerospace engineering ,business ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences - Abstract
Several energetic particle sensors designed to make measurements in the current decade are described and their technology and capabilities discussed and demonstrated. Most of these instruments are already on orbit or approaching launch. These include the Magnetic Electron Ion Spectrometers (MagEIS) and the Relativistic Electron Proton Telescope (REPT) that are flying on the Van Allen Probes, the Fly's Eye Electron Proton Spectrometers (FEEPS) flying on the Magnetospheric Multiscale (MMS) mission, and Dosimeters flying on the AC6 Cubesat mission. We focus mostly on the electron measurement capability of these sensors while providing summary comments of their ion measurement capabilities if they have any.
- Published
- 2016
24. Energy limits of electron acceleration in the plasma sheet during substorms: A case study with the Magnetospheric Multiscale (MMS) mission
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Rumi Nakamura, Daniel Schmid, Drew Turner, Roy B. Torbert, Geoffrey D. Reeves, Levon A. Avanov, Christopher T. Russell, Robert J. Strangeway, John C. Dorelli, Andrei Runov, Craig J. Pollock, Daniel N. Baker, Frederick Wilder, Barry Mauk, Ian J. Cohen, Allison Jaynes, J. B. Blake, Barbara L. Giles, Harlan E. Spence, James L. Burch, D. J. Gershman, J. V. Craft, J. F. Fennell, Vassilis Angelopoulos, A. V. Artemyev, and J. H. Clemmons
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Physics ,Range (particle radiation) ,010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,Plasma sheet ,Electron ,Geophysics ,Threshold energy ,Betatron ,01 natural sciences ,Computational physics ,Particle acceleration ,Physics::Space Physics ,0103 physical sciences ,Substorm ,General Earth and Planetary Sciences ,Magnetospheric Multiscale Mission ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences - Abstract
We present multipoint observations of earthward moving dipolarization fronts and energetic particle injections from NASA's Magnetospheric Multiscale mission with a focus on electron acceleration. From a case study during a substorm on 02 August 2015, we find that electrons are only accelerated over a finite energy range, from a lower energy threshold at ~7–9 keV up to an upper energy cutoff in the hundreds of keV range. At energies lower than the threshold energy, electron fluxes decrease, potentially due to precipitation by strong parallel electrostatic wavefields or initial sources in the lobes. Electrons at energies higher than the threshold are accelerated cumulatively by a series of impulsive magnetic dipolarization events. This case demonstrates how the upper energy cutoff increases, in this case from ~130 keV to >500 keV, with each dipolarization/injection during sustained activity. We also present a simple model accounting for these energy limits that reveals that electron energization is dominated by betatron acceleration.
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- 2016
25. Inner zone and slot electron radial diffusion revisited
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T. P. O'Brien, J. B. Blake, Seth G. Claudepierre, James L. Roeder, Drew Turner, J. H. Clemmons, Timothy Guild, and J. F. Fennell
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Physics ,010504 meteorology & atmospheric sciences ,Scattering ,Coordinate system ,Electron ,01 natural sciences ,Computational physics ,symbols.namesake ,Geophysics ,Classical mechanics ,Van Allen radiation belt ,Phase space ,0103 physical sciences ,symbols ,General Earth and Planetary Sciences ,Van Allen Probes ,Astrophysics::Earth and Planetary Astrophysics ,Pitch angle ,Diffusion (business) ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences - Abstract
Using recent data from NASA's Van Allen Probes, we estimate the quiet time radial diffusion coefficients for electrons in the inner radiation belt (L
- Published
- 2016
26. Microinjections observed by MMS FEEPS in the dusk to midnight region
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J. B. Blake, Daniel N. Baker, Ian J. Cohen, Drew Turner, Barbara L. Giles, Harlan E. Spence, Allison Jaynes, J. H. Clemmons, Barry Mauk, James L. Burch, W. R. Paterson, Roy B. Torbert, J. V. Craft, J. F. Fennell, Robert J. Strangeway, Geoffrey D. Reeves, Joseph Westlake, and C. Lemon
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Physics ,Geophysics ,010504 meteorology & atmospheric sciences ,Meteorology ,Midnight ,0103 physical sciences ,Microinjections ,General Earth and Planetary Sciences ,Dusk ,Atmospheric sciences ,010303 astronomy & astrophysics ,01 natural sciences ,0105 earth and related environmental sciences - Published
- 2016
27. Observations of energetic particle escape at the magnetopause: Early results from the MMS Energetic Ion Spectrometer (EIS)
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Brian J. Anderson, Ian J. Cohen, Geoffrey D. Reeves, Allison Jaynes, J. T. Niehof, Barry Mauk, Joseph Westlake, Daniel N. Baker, Robert J. Strangeway, K. J. Trattner, James L. Burch, Roy B. Torbert, Werner Magnes, Barbara L. Giles, Craig J. Pollock, David G. Sibeck, J. V. Craft, Christopher T. Russell, J. F. Fennell, S. A. Fuselier, J. H. Clemmons, Harlan E. Spence, Drew Turner, and J. B. Blake
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Physics ,010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,Magnetosphere ,Magnetic reconnection ,Geophysics ,Astrophysics ,Electron ,01 natural sciences ,Magnetic field ,Ion ,Magnetosheath ,Physics::Space Physics ,0103 physical sciences ,General Earth and Planetary Sciences ,Magnetopause ,Pitch angle ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences - Abstract
Energetic (greater than tens of keV) magnetospheric particle escape into the magnetosheath occurs commonly, irrespective of conditions that engender reconnection and boundary-normal magnetic fields. A signature observed by the Magnetospheric Multiscale (MMS) mission, simultaneous monohemispheric streaming of multiple species (electrons, H+, Hen+), is reported here as unexpectedly common in the dayside, dusk quadrant of the magnetosheath even though that region is thought to be drift-shadowed from energetic electrons. This signature is sometimes part of a pitch angle distribution evolving from symmetric in the magnetosphere, to asymmetric approaching the magnetopause, to monohemispheric streaming in the magnetosheath. While monohemispheric streaming in the magnetosheath may be possible without a boundary-normal magnetic field, the additional pitch angle depletion, particularly of electrons, on the magnetospheric side requires one. Observations of this signature in the dayside dusk sector imply that the static picture of magnetospheric drift-shadowing is inappropriate for energetic particle dynamics in the outer magnetosphere.
- Published
- 2016
28. High-resolution modeling of the cusp density anomaly: Response to particle and Joule heating under typical conditions
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Richard L. Walterscheid, James H. Hecht, Douglas G. Brinkman, and J. H. Clemmons
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Physics ,Cusp (singularity) ,010504 meteorology & atmospheric sciences ,High resolution ,Geophysics ,01 natural sciences ,Space and Planetary Science ,0103 physical sciences ,Particle ,Upwelling ,Anomaly (physics) ,Thermosphere ,Joule heating ,010303 astronomy & astrophysics ,Neutral density filter ,0105 earth and related environmental sciences - Published
- 2016
29. VISIONS remote observations of a spatially-structured filamentary source of energetic neutral atoms near the polar cap boundary during an auroral substorm
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Michael R. Collier, John W. Keller, J. McLain, R. F. Pfaff, Joe Kujawski, M. Zettergren, Douglas E. Rowland, Jeffrey Klenzing, J. H. Clemmons, and Dennis J. Chornay
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Physics ,Atmospheric Science ,education.field_of_study ,Energetic neutral atom ,Population ,Aerospace Engineering ,Astronomy and Astrophysics ,Ionospheric sounding ,Spectral line ,Ion ,Solar wind ,Geophysics ,Space and Planetary Science ,Physics::Space Physics ,Substorm ,General Earth and Planetary Sciences ,Outflow ,Atomic physics ,education - Abstract
We report initial results from the VISualizing Ion Outflow via Neutral atom imaging during a Substorm (VISIONS) rocket that flew through and near several regions of enhanced auroral activity and also sensed regions of ion outflow both remotely and directly. The observed neutral atom fluxes were largest at the lower energies and generally higher in the auroral zone than in the polar cap. In this paper, we focus on data from the latter half of the VISIONS trajectory when the rocket traversed the polar cap region. During this period, many of the energetic neutral atom spectra show a peak at 100 electronvolts. Spectra with peaks around 100 electronvolts are also observed in the Electrostatic Ion Analyzer (EIA) data consistent with these ions comprising the source population for the energetic neutral atoms. The EIA observations of this low energy population extend only over a few tens of kilometers. Furthermore, the directionality of the arriving energetic neutral atoms is consistent with either this spatially localized source of energetic ions extending from as low as about 300 kilometers up to above 600 kilometers or a larger source of energetic ions to the southwest.
- Published
- 2015
30. Autogenous and efficient acceleration of energetic ions upstream of Earth's bow shock
- Author
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Daniel N. Baker, Adnane Osmane, Christopher T. Russell, J. B. Blake, Steven J. Schwartz, Robert J. Strangeway, Ian J. Cohen, T. W. Leonard, J. H. Clemmons, Allison Jaynes, J. M. Broll, R. G. Gomez, Terry Z. Liu, Roy B. Torbert, Daniel J. Gershman, Barry Mauk, Drew Turner, Barbara L. Giles, Joseph Westlake, Levon A. Avanov, S. A. Fuselier, Lynn B. Wilson, James L. Burch, and J. F. Fennell
- Subjects
Physics ,education.field_of_study ,Multidisciplinary ,010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,Population ,Magnetosphere ,Cosmic ray ,Fermi acceleration ,01 natural sciences ,Article ,Computational physics ,Foreshock ,Solar wind ,0103 physical sciences ,Physics::Space Physics ,Astrophysics::Earth and Planetary Astrophysics ,Bow shock (aerodynamics) ,Interplanetary magnetic field ,education ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences - Abstract
Earth and its magnetosphere are immersed in the supersonic flow of the solar-wind plasma that fills interplanetary space. As the solar wind slows and deflects to flow around Earth, or any other obstacle, a ‘bow shock’ forms within the flow. Under almost all solar-wind conditions, planetary bow shocks such as Earth’s are collisionless, supercritical shocks, meaning that they reflect and accelerate a fraction of the incident solar-wind ions as an energy dissipation mechanism1,2, which results in the formation of a region called the ion foreshock3. In the foreshock, large-scale, transient phenomena can develop, such as ‘hot flow anomalies’4–9, which are concentrations of shock-reflected, suprathermal ions that are channelled and accumulated along certain structures in the upstream magnetic field. Hot flow anomalies evolve explosively, often resulting in the formation of new shocks along their upstream edges5,10, and potentially contribute to particle acceleration11–13, but there have hitherto been no observations to constrain this acceleration or to confirm the underlying mechanism. Here we report observations of a hot flow anomaly accelerating solar-wind ions from roughly 1–10 kiloelectronvolts up to almost 1,000 kiloelectronvolts. The acceleration mechanism depends on the mass and charge state of the ions and is consistent with first-order Fermi acceleration14,15. The acceleration that we observe results from only the interaction of Earth’s bow shock with the solar wind, but produces a much, much larger number of energetic particles compared to what would typically be produced in the foreshock from acceleration at the bow shock. Such autogenous and efficient acceleration at quasi-parallel bow shocks (the normal direction of which are within about 45 degrees of the interplanetary magnetic field direction) provides a potential solution to Fermi’s ‘injection problem’, which requires an as-yet-unexplained seed population of energetic particles, and implies that foreshock transients may be important in the generation of cosmic rays at astrophysical shocks throughout the cosmos. Observations of a hot flow anomaly accelerating solar-wind ions suggest a mechanism for such acceleration—a Fermi acceleration trap caused by Earth’s bow shock interacting with the solar wind.
- Published
- 2018
31. Scientific Objectives of Electron Losses and Fields INvestigation Onboard Lomonosov Satellite
- Author
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Christopher T. Russell, Drew Turner, Yuri Shprits, I. V. Yashin, D. Leneman, Alexander Drozdov, Vladimir Kalegaev, P. Cruce, Robert J. Strangeway, Andrei Runov, Mikhail Panasyuk, Ingo Michaelis, Vasily Petrov, V. Angelopoulos, C. L. Russell, R. Caron, Ilya Nazarkov, and J. H. Clemmons
- Subjects
010504 meteorology & atmospheric sciences ,business.industry ,Astrophysics::Instrumentation and Methods for Astrophysics ,Magnetosphere ,Astronomy and Astrophysics ,Electron ,Radiation ,01 natural sciences ,Atmosphere ,symbols.namesake ,Planetary science ,Space and Planetary Science ,Van Allen radiation belt ,Physics::Space Physics ,0103 physical sciences ,symbols ,Environmental science ,CubeSat ,Satellite ,Astrophysics::Earth and Planetary Astrophysics ,Aerospace engineering ,business ,010303 astronomy & astrophysics ,Physics::Atmospheric and Oceanic Physics ,0105 earth and related environmental sciences - Abstract
The objective of the Electron Losses and Fields INvestigation on board the Lomonosov satellite (ELFIN-L) project is to determine the energy spectrum of precipitating energetic electrons and ions and, together with other polar-orbiting and equatorial missions, to better understand the mechanisms responsible for scattering these particles into the atmosphere. This mission will provide detailed measurements of the radiation environment at low altitudes. The 400–500 km sun-synchronous orbit of Lomonosov is ideal for observing electrons and ions precipitating into the atmosphere. This mission provides a unique opportunity to test the instruments. Similar suite of instruments will be flown in the future NSF- and NASA-supported spinning CubeSat ELFIN satellites which will augment current measurements by providing detailed information on pitch-angle distributions of precipitating and trapped particles.
- Published
- 2018
32. LAICE CubeSat mission for gravity wave studies
- Author
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R. L. Davidson, Bindu B. Jagannatha, Cameron Orr, Rebecca Bishop, Lucy Fanelli, Erik Kroeker, R. V. Robertson, Daniel Martin, Gary R. Swenson, Stephen Noel, Gregory Earle, C. Fish, Alexander Ghosh, J. H. Clemmons, Sharon L. Vadas, Peter Marquis, Vidur Garg, and John Westerhoff
- Subjects
Physics ,Atmospheric Science ,business.industry ,Astrophysics::Instrumentation and Methods for Astrophysics ,Airglow ,Aerospace Engineering ,Astronomy and Astrophysics ,Photometer ,law.invention ,Atmosphere ,Geophysics ,Space and Planetary Science ,law ,Physics::Space Physics ,International Space Station ,General Earth and Planetary Sciences ,CubeSat ,Astrophysics::Earth and Planetary Astrophysics ,Gravity wave ,Ionosphere ,Aerospace engineering ,Thermosphere ,business ,Remote sensing - Abstract
The Lower Atmosphere/Ionosphere Coupling Experiment (LAICE) CubeSat mission will focus on understanding the interaction of atmospheric gravity waves generated by weather systems in the lower atmosphere with the mesosphere, lower thermosphere, and ionosphere (MLTI). Specifically, LAICE will focus on the energy and momentum delivered by these waves and attempt to connect the wave sources and the wave effects in three widely different altitude ranges, substantially adding to our knowledge of critical coupling processes between disparate atmospheric regions. The LAICE mission consists of a 6U CubeSat with a four-instrument payload. The retarding potential analyzer (RPA) will provide in-situ ion density and temperature measurements. A four-channel photometer will measure density and temperature variations in the mesosphere through observations of O 2 (0, 0) Atmospheric band and O 2 Herzberg I band airglows. There are two pressure sensors that comprise the Space Pressure Suite (SPS): the Space Neutral Pressure Instrument (SNeuPI) and the LAICE Ionization gauge Neutral Atmosphere Sensor (LINAS). Both will provide neutral density measurements, but SNeuPI is a prototype sensor that will be validated by LINAS. This CubeSat mission, scheduled for launch in early 2016 from the International Space Station, provides a cost-effective approach to measuring low altitude in-situ parameters along with simultaneous imaging that is capable of addressing the fundamental questions of atmospheric gravity wave coupling in the MLTI region.
- Published
- 2015
33. Long-Term Galactic Cosmic Ray Environment Response of Plasma Analyzers on High-Altitude Spacecraft
- Author
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Joseph F. Fennell, J. Bernard Blake, Timothy Guild, James L. Roeder, Margaret W. Chen, and J. H. Clemmons
- Subjects
Physics ,Dosimeter ,Spacecraft ,Proton ,Spectrometer ,business.industry ,Aerospace Engineering ,Astronomy ,Cosmic ray ,Astrophysics ,Effects of high altitude on humans ,Solar cycle ,Space and Planetary Science ,Physics::Space Physics ,Astrophysics::Earth and Planetary Astrophysics ,business ,Molniya orbit - Abstract
The long-term galactic cosmic ray (GCR) environment response of the dosimeter and surface-charging monitors on two high-altitude satellites called F1 and F2 is analyzed. These satellites also host the National Aeronautics and Space Administration’s Two Wide-angle Imaging Neutral-atom Spectrometers. The trend of the GCR intensity with solar cycle from year 2006 through 2012 is estimated from in-situ Advanced Composition Explorer (ACE) and Ulysses data. The dosimeter average 25–45 MeV proton counts and the >2.4 MeV electron counts at apogee follow the expected GCR solar-cycle trend, but the best-fit variations are smaller than estimated from ACE heavy ion GCR data. The surface-charging monitor average minima ion counts at apogee on F1, one of the host spacecraft, are consistent with the solar-cycle variation of Ulysses proton GCR counts. Linear fits to the F1 surface-charging monitor response to the GCR environment that may be subtracted from the measured counts before conversion to particle fluxes are pro...
- Published
- 2015
34. A background correction algorithm for Van Allen Probes MagEIS electron flux measurements
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Harlan E. Spence, T. Mulligan, Brian A. Larsen, J. B. Blake, Reiner Friedel, Geoffrey D. Reeves, Michael G. Henderson, J. H. Clemmons, J. E. Mazur, Seth G. Claudepierre, M. D. Looper, T. P. O'Brien, J. F. Fennell, and James L. Roeder
- Subjects
Physics ,Spacecraft ,Spectrometer ,business.industry ,Bremsstrahlung ,Electron ,Spacecraft design ,symbols.namesake ,Geophysics ,Space and Planetary Science ,Van Allen radiation belt ,symbols ,Van Allen Probes ,business ,Algorithm ,Space environment - Abstract
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-MeV 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).
- Published
- 2015
35. Van Allen Probes show that the inner radiation zone contains no MeV electrons: ECT/MagEIS data
- Author
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J. H. Clemmons, Daniel N. Baker, T. P. O'Brien, Harlan E. Spence, J. B. Blake, Seth G. Claudepierre, J. F. Fennell, and Geoffrey D. Reeves
- Subjects
Physics ,Spectrometer ,Astrophysics::High Energy Astrophysical Phenomena ,Electron ,Plasma ,Radiation zone ,Ion ,symbols.namesake ,Geophysics ,Van Allen radiation belt ,symbols ,General Earth and Planetary Sciences ,Particle ,Van Allen Probes ,Atomic physics - Abstract
We present Van Allen Probe observations of electrons in the inner radiation zone. The measurements were made by the Energetic Particle, Composition, and Thermal Plasma/Magnetic Electron Ion Spectrometer (MagEIS) sensors that were designed to measure electrons with the ability to remove unwanted signals from penetrating protons, providing clean measurements. No electrons >900 keV were observed with equatorial fluxes above background (i.e., >0.1 el/(cm2 s sr keV)) in the inner zone. The observed fluxes are compared to the AE9 model and CRRES observations. Electron fluxes
- Published
- 2015
36. On the use of drift echoes to characterize on-orbit sensor discrepancies
- Author
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J. B. Blake, Seth G. Claudepierre, James L. Roeder, Daniel N. Baker, Matina Gkioulidou, M. D. Looper, Louis J. Lanzerotti, D. G. Mitchell, Geoffrey D. Reeves, Shrikanth Kanekal, J. W. Manweiler, J. F. Fennell, J. H. Clemmons, Harlan E. Spence, and T. P. O'Brien
- Subjects
Physics ,Spacecraft ,business.industry ,Echo (computing) ,Computational physics ,symbols.namesake ,Geophysics ,Space and Planetary Science ,Van Allen radiation belt ,symbols ,Orbit (dynamics) ,Satellite ,Van Allen Probes ,Dispersion (water waves) ,business ,Energy (signal processing) ,Remote sensing - Abstract
We describe a method for using drift echo signatures in on-orbit data to resolve discrepancies between different measurements of particle flux. The drift period has a well-defined energy dependence, which gives rise to time dispersion of the echoes. The dispersion can then be used to determine the effective energy for one or more channels given each channel's drift period and the known energy for a reference channel. We demonstrate this technique on multiple instruments from the Van Allen Probes mission. Drift echoes are only easily observed at high energies (100 s keV to multiple MeV), where several drift periods occur before the observing satellite has moved on or the global magnetic conditions have changed. We describe a first-order correction for spacecraft motion. The drift echo technique has provided a significant clue in resolving substantial flux discrepancies between two instruments measuring fluxes near 2 MeV.
- Published
- 2015
37. Multipoint Observations of Energetic Particle Injections and Substorm Activity During a Conjunction Between Magnetospheric Multiscale (MMS) and Van Allen Probes
- Author
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Christine Gabrielse, Daniel N. Baker, O. Le Contel, Roy B. Torbert, Robert J. Strangeway, T. W. Leonard, Craig Kletzing, Matina Gkioulidou, Vassilis Angelopoulos, Ian J. Cohen, Allison Jaynes, J. B. Blake, Seth G. Claudepierre, Drew Turner, Barry Mauk, Geoffrey D. Reeves, J. F. Fennell, Aleksandr Ukhorskiy, James L. Burch, J. H. Clemmons, Harlan E. Spence, Laboratoire de Physique des Plasmas (LPP), Université Paris-Saclay-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École polytechnique (X)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)
- Subjects
Physics ,010504 meteorology & atmospheric sciences ,Plasma sheet ,Magnetosphere ,Geophysics ,01 natural sciences ,L-shell ,Computational physics ,symbols.namesake ,Solar wind ,Earth's magnetic field ,13. Climate action ,Space and Planetary Science ,[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph] ,Van Allen radiation belt ,0103 physical sciences ,Substorm ,Physics::Space Physics ,symbols ,Van Allen Probes ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences - Abstract
International audience; This study examines multipoint observations during a conjunction between Magnetospheric Multiscale (MMS) and Van Allen Probes on 7 April 2016 in which a series of energetic particle injections occurred. With complementary data from Time History of Events and Macroscale Interactions during Substorms, Geotail, and Los Alamos National Laboratory spacecraft in geosynchronous orbit (16 spacecraft in total), we develop new insights on the nature of energetic particle injections associated with substorm activity. Despite this case involving only weak substorm activity (maximum AE
- Published
- 2017
38. Van Allen Probes observations of direct wave‐particle interactions
- Author
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Craig Kletzing, Brian A. Larsen, Herbert O. Funsten, J. H. Clemmons, J. S. G. Claudepierre, Harlan E. Spence, Geoffrey D. Reeves, John R. Wygant, William S. Kurth, J. B. Blake, George Hospodarsky, James L. Roeder, Michael G. Henderson, and J. F. Fennell
- Subjects
Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Cyclotron ,Plasmasphere ,Plasma ,Electron ,law.invention ,Geophysics ,Flux (metallurgy) ,law ,Quasiperiodic function ,Physics::Space Physics ,General Earth and Planetary Sciences ,Van Allen Probes ,Pitch angle ,Atomic physics - Abstract
Quasiperiodic increases, or “bursts,” of 17–26 keV electron fluxes in conjunction with chorus wave bursts were observed following a plasma injection on 13 January 2013. The pitch angle distributions changed during the burst events, evolving from sinN(α) to distributions that formed maxima at α = 75–80°, while fluxes at 90° and
- Published
- 2014
39. An empirically observed pitch-angle diffusion eigenmode in the Earth's electron belt nearL* = 5.0
- Author
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James L. Roeder, J. H. Clemmons, J. B. Blake, Seth G. Claudepierre, T. P. O'Brien, Daniel N. Baker, Harlan E. Spence, Joseph F. Fennell, and Geoffrey D. Reeves
- Subjects
Physics ,Scattering ,Electron ,Exponential function ,Computational physics ,Geophysics ,Classical mechanics ,Exponential growth ,General Earth and Planetary Sciences ,High Energy Physics::Experiment ,Van Allen Probes ,Pitch angle ,Exponential decay ,Diffusion (business) - Abstract
Using data from NASA's Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is elastic pitch angle scattering, which itself depends on energy and L*. We invert the shape of the observed eigenmode to obtain an approximate shape of the pitch angle diffusion coefficient and show excellent agreement with diffusion by plasmaspheric hiss. Our results suggest that empirically derived eigenmodes provide a powerful diagnostic of the dynamic processes behind exponential decays.
- Published
- 2014
40. The Fly’s Eye Energetic Particle Spectrometer (FEEPS) Sensors for the Magnetospheric Multiscale (MMS) Mission
- Author
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J. B. Blake, B. H. Mauk, D. N. Baker, P. Carranza, J. H. Clemmons, J. Craft, W. R. Crain, A. Crew, Y. Dotan, J. F. Fennell, R. H. Friedel, L. M. Friesen, F. Fuentes, R. Galvan, C. Ibscher, A. Jaynes, N. Katz, M. Lalic, A. Y. Lin, D. M. Mabry, T. Nguyen, C. Pancratz, M. Redding, G. D. Reeves, S. Smith, H. E. Spence, and J. Westlake
- Published
- 2016
41. The Energetic Particle Detector (EPD) Investigation and the Energetic Ion Spectrometer (EIS) for the Magnetospheric Multiscale (MMS) Mission
- Author
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B. H. Mauk, J. B. Blake, D. N. Baker, J. H. Clemmons, G. D. Reeves, H. E. Spence, S. E. Jaskulek, C. E. Schlemm, L. E. Brown, S. A. Cooper, J. V. Craft, J. F. Fennell, R. S. Gurnee, C. M. Hammock, J. R. Hayes, P. A. Hill, G. C. Ho, J. C. Hutcheson, A. D. Jacques, S. Kerem, D. G. Mitchell, K. S. Nelson, N. P. Paschalidis, E. Rossano, M. R. Stokes, and J. H. Westlake
- Published
- 2016
42. Van Allen Probes observation of localized drift resonance between poloidal mode ultra‐low frequency waves and 60 keV electrons
- Author
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Herbert O. Funsten, Ian R. Mann, Geoffrey D. Reeves, Robert J. MacDowall, R. H. W. Friedel, J. H. Clemmons, William S. Kurth, Mary K. Hudson, James L. Roeder, Charles W. Smith, Daniel N. Baker, Harlan E. Spence, Kazue Takahashi, John R. Wygant, Craig Kletzing, J. B. Blake, Seth G. Claudepierre, Michael G. Henderson, and J. F. Fennell
- Subjects
Physics ,Toroid ,010504 meteorology & atmospheric sciences ,Resonance ,Electron ,01 natural sciences ,Computational physics ,symbols.namesake ,Geophysics ,Amplitude ,Van Allen radiation belt ,0103 physical sciences ,symbols ,General Earth and Planetary Sciences ,Van Allen Probes ,Pitch angle ,Atomic physics ,010303 astronomy & astrophysics ,Ultra low frequency ,0105 earth and related environmental sciences - Abstract
Summary of wave and particle observations that suggest drift resonance between magnetospheric ULF wavesand energetic electrons. (a) Residual electron flux ( J – 0 J 0 ) from MagEIS-A. (Figure 2a, inset) The amplitude (solid trace) andphase(dashedtrace)oftheresidualfluxoscillations.(b)ThepoloidalcomponentofthemagneticfieldfromtheEMFISIS-Amagnetometer. (c) East-west component of the Earth’s magnetic field measured at the Dawson City (CARISMA) groundmagnetometer station. (d) Pitch angle spectrogram from the 80 keV channel on MagEIS-A.that magnetospheric ULF waves are never entirely poloidalor toroidal, as the wave modes do not fully decouple inan asymmetric field. The poloidal electric field component, E ' , cannot be reliably measured during this event (see thesupporting information). However, ULF electric field oscil-lations are observed in the two available field components,at the same period as the observed poloidal magnetic fieldoscillations. Figure 1g shows the profile of the electronnumber density derived from the EMFISIS-A upper hybridline during this event. The Van Allen Probe A spacecraft isinsideofthedenseplasmasphereatthebeginningofthetimeinterval shown and moves out of the plasmaspheric regionas the spacecraft traverses higher L shells towards apogee.Between 15:45:00 and 16:00:00 UTC, when the poloidalmode ULF wave is observed, we compute the local electronnumber density to be 50 cm
- Published
- 2013
43. Rapid, highly structured meridional winds and their modulation by non migrating tides: Measurements from the Streak mission
- Author
-
Richard L. Walterscheid, Andrew B. Christensen, J. H. Clemmons, and Rebecca Bishop
- Subjects
Streak ,Zonal and meridional ,Geophysics ,F region ,Earth's magnetic field ,Space and Planetary Science ,Physics::Space Physics ,Astrophysics::Earth and Planetary Astrophysics ,Thermosphere ,Ionosphere ,Longitude ,Physics::Atmospheric and Oceanic Physics ,Geology ,Convection cell - Abstract
[1] Measurements of the Earth's low latitude thermosphere returned by the ionization gauge on the Streak mission are reported and discussed. The measurements are of the amount of gas rammed into the sensor by its passage through the thermospheric medium. They were obtained in the dusk sector in the altitude range 130–330 km and are shown to be strongly structured by the geomagnetic field. Similarities to the structure of the equatorial ionization anomaly are discussed. The structure is interpreted as being due to rapid (several hundred meters per second) meridional winds having an antisymmetric pattern with respect to the geomagnetic equator. The measurements are interpreted in light of results from other missions and are shown to fit well with ideas based on complementary measurements from the Dynamics Explorer 2 mission discussed as the Equatorial Temperature and Wind Anomaly. Several features of these winds are described and discussed, including their altitude dependence, how they form convection cells that extend to high latitude, and how the wind amplitudes vary with geographic longitude with an apparent wavenumber one variation. The latter characteristic is shown to be consistent with being the signature of tidal variations observed by others. Approximate calculations utilizing published values for the pertinent parameters are used to show that heating from the dissipation due to ion drag within the ionospheric F region is a dominant driver of the inferred winds.
- Published
- 2013
44. Future Atmosphere-Ionosphere-Magnetosphere Coupling Study Requirements
- Author
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Larry Kepko, Christopher Cully, Thomas E. Moore, Eric Donovan, Jeffrey P. Thayer, Douglas E. Rowland, Gregory Earle, Rod Heelis, Glyn Collinson, Marc Lessard, Kevin S. Brenneman, J. H. Clemmons, Joshua Semeter, Craig J. Pollock, L. M. Kistler, George V. Khazanov, Michael J. Nicolls, C. R. Chappell, Ennio R. Sanchez, Daniel J. Gershman, Robert F. Pfaff, Robert W. Schunk, David J. Knudsen, Elizabeth MacDonald, and Robert J. Strangeway
- Subjects
Atmosphere ,Physics ,Coupling (physics) ,010504 meteorology & atmospheric sciences ,Magnetosphere ,Interplanetary magnetic field ,Ionosphere ,010502 geochemistry & geophysics ,01 natural sciences ,0105 earth and related environmental sciences ,Computational physics - Published
- 2016
45. Electron-scale measurements of magnetic reconnection in space
- Author
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Rumi Nakamura, Drew Turner, Michael Shay, Yu. V. Khotyaintsev, J. F. Fennell, K. A. Goodrich, Ian J. Cohen, Michael O. Chandler, Per-Arne Lindqvist, Göran Marklund, Klaus Torkar, Shan Wang, Martin V. Goldman, Allison Jaynes, J. H. Clemmons, James Drake, D. T. Young, J. B. Blake, Daniel J. Gershman, K. J. Trattner, M. Steller, S. M. Petrinec, Frederick Wilder, Barry Mauk, Tai Phan, Wolfgang Baumjohann, John C. Dorelli, Jonathan Eastwood, Levon A. Avanov, Yoshifumi Saito, Benoit Lavraud, Matthew R. Argall, T. E. Moore, L. J Chen, Jerry Goldstein, David Newman, Mitsuo Oka, Craig J. Pollock, James L. Burch, Christopher T. Russell, Robert E. Ergun, Michael Hesse, Patricia H. Reiff, Roy B. Torbert, Daniel N. Baker, Stephen A. Fuselier, W. S. Lewis, Barbara L. Giles, Paul Cassak, Robert J. Strangeway, Werner Magnes, Victoria N. Coffey, Science and Technology Facilities Council (STFC), and Science and Technology Facilities Council [2006-2012]
- Subjects
010504 meteorology & atmospheric sciences ,General Science & Technology ,Magnetosphere ,Astrophysics ,ACCELERATION ,01 natural sciences ,Physics::Plasma Physics ,DIFFUSION REGION ,0103 physical sciences ,EARTHS MAGNETOPAUSE ,Interplanetary magnetic field ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,MULTISCALE MMS MISSION ,Physics ,Science & Technology ,Multidisciplinary ,Magnetic energy ,Demagnetizing field ,Magnetic reconnection ,MAGNETOSPHERIC MULTISCALE ,Magnetic field ,Computational physics ,Multidisciplinary Sciences ,Physics::Space Physics ,Science & Technology - Other Topics ,Astrophysical plasma ,Magnetospheric Multiscale Mission - Abstract
著者人数: 52名, 資料番号: SA1160034000
- Published
- 2016
46. High efficiency fourth-harmonic generation from nanosecond fiber master oscillator power amplifier
- Author
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Todd S. Rose, Steven M. Beck, Xiaodong Mu, J. H. Clemmons, Paul Steinvurzel, and William T. Lotshaw
- Subjects
Ytterbium ,Materials science ,business.industry ,Amplifier ,Single-mode optical fiber ,Second-harmonic generation ,chemistry.chemical_element ,02 engineering and technology ,Nanosecond ,021001 nanoscience & nanotechnology ,01 natural sciences ,010309 optics ,Optics ,Narrowband ,chemistry ,Fiber laser ,0103 physical sciences ,Optoelectronics ,0210 nano-technology ,business ,Gain stage - Abstract
We demonstrate high power, deep ultraviolet (DUV) conversion to 266 nm through frequency quadrupling of a nanosecond pulse width 1064 nm fiber master oscillator power amplifier (MOPA). The MOPA system uses an Yb-doped double-clad polarization-maintaining large mode area tapered fiber as the final gain stage to generate 0.5-mJ, 10 W, 1.7- ns single mode pulses at a repetition rate of 20 kHz with measured spectral bandwidth of 10.6 GHz (40 pm), and beam qualities of Mx 2=1.07 and My 2=1.03, respectively. Using LBO and BBO crystals for the second-harmonic generation (SHG) and fourth-harmonic generation (FHG), we have achieved 375 μJ (7.5 W) and 92.5 μJ (1.85 W) at wavelengths of 532 nm and 266 nm, respectively. To the best of our knowledge these are the highest narrowband infrared, green and UV pulse energies obtained to date from a fully spliced fiber amplifier. We also demonstrate high efficiency SHG and FHG with walk-off compensated (WOC) crystal pairs and tightly focused pump beam. An SHG efficiency of 75%, FHG efficiency of 47%, and an overall efficiency of 35% from 1064 nm to 266 nm are obtained.
- Published
- 2016
47. The Ionization Gauge Investigation for the Streak Mission
- Author
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Y. Dotan, Rebecca Bishop, L. M. Friesen, M. Ben-Ami, J. H. Clemmons, and N. Katz
- Subjects
Physics ,business.industry ,Streak ,Astronomy and Astrophysics ,Gauge (firearms) ,Orbital operations ,Pressure sensor ,Optics ,Low earth orbit ,Space and Planetary Science ,Ionization ,Physics::Space Physics ,Astrophysics::Earth and Planetary Astrophysics ,Thermosphere ,Aerospace engineering ,business ,Host (network) - Abstract
An experimental investigation into the characteristics and dynamics of the Earth’s thermosphere using a low-Earth orbiting platform is described. An overview of the investigation and its host mission, Streak, is given. The centerpiece of the investigation, a sensitive pressure sensor that utilizes an ionization gauge, is described in detail. Presented are the observational objectives of the instrument, its principles of measurement, and a technical description of its design and implementation. Orbital operations are discussed, and an early sample of the returned measurements is presented.
- Published
- 2009
48. The Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) NASA Mission-of-Opportunity
- Author
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Ruth M. Skoug, Herbert O. Funsten, H. Henkel, M. Reno, D. J. Mabry, Michelle F. Thomsen, C. Urdiales, James L. Burch, Mike Gruntman, M.K. Young, S. M. Ritzau, Kai Viherkanto, D. T. Everett, B. Blake, S. Weidner, R. Harbaugh, Pontus Brandt, L. M. Friesen, J. H. Clemmons, Uwe Nass, T. S. Sotirelis, R. W. Harper, Earl Scime, J. R. Baldonado, Christer Holmlund, S. Pope, Donald G. Mitchell, David J. McComas, Robert DeMajistre, G. Lay, D. M. Delapp, Jochen H. Zoennchen, Phil Valek, Edmond C. Roelof, W.R. Crain, C. J. Pollock, Tomi Ylikorpi, M. Sivjee, Frederic Allegrini, Jerry Goldstein, and Hans-Jörg Fahr
- Subjects
Physics ,Energetic neutral atom ,Spacecraft ,Spectrometer ,business.industry ,Astrophysics::Instrumentation and Methods for Astrophysics ,Magnetosphere ,Astronomy and Astrophysics ,ENA ,ENA instrumentation ,Charged particle ,Space plasma calibration facility ,Planetary science ,Space and Planetary Science ,Physics::Space Physics ,Calibration ,business ,Energetic neutral atom imaging ,Geocorona ,Remote sensing - Abstract
Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) is a NASA Explorer Mission-of-Opportunity to stereoscopically image the Earth’s magnetosphere for the first time. TWINS extends our understanding of magnetospheric structure and processes by providing simultaneous Energetic Neutral Atom (ENA) imaging from two widely separated locations. TWINS observes ENAs from 1–100 keV with high angular (∼4°×4°) and time (∼1-minute) resolution. The TWINS Ly-α monitor measures the geocoronal hydrogen density to aid in ENA analysis while environmental sensors provide contemporaneous measurements of the local charged particle environments. By imaging ENAs with identical instruments from two widely spaced, high-altitude, high-inclination spacecraft, TWINS enables three-dimensional visualization of the large-scale structures and dynamics within the magnetosphere for the first time. This “instrument paper” documents the TWINS design, construction, calibration, and initial results. Finally, the appendix of this paper describes and documents the Southwest Research Institute (SwRI) instrument calibration facility; this facility was used for all TWINS instrument-level calibrations.
- Published
- 2009
49. Computational Analysis of High-Altitude Ionization Gauge Flight Measurements
- Author
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Chunpei Cai, James H. Hecht, J. H. Clemmons, Iain D. Boyd, and Quanhua Sun
- Subjects
Physics ,Computer simulation ,business.industry ,Payload ,Astrophysics::Instrumentation and Methods for Astrophysics ,Aerospace Engineering ,Compressible flow ,Computational physics ,Physics::Fluid Dynamics ,Free molecular flow ,Space and Planetary Science ,Ionization ,Bow shock (aerodynamics) ,Direct simulation Monte Carlo ,Aerospace engineering ,business ,Stagnation pressure - Abstract
The rarefied, three-dimensional flows experienced during the turbulent oxygen mixing experiment (TOMEX) at altitudes between 85 and 143 km are simulated using the direct simulation Monte Carlo (DSMC) method. The present study focuses on ionization gauge measurements obtained by TOMEX. The payload is, thus, modeled in detail, and the simulations employ complex meshes. The simulations show that a bow shock wave is generated in front of the payload at low altitude that becomes diffusive at higher altitudes. When the altitude increases, the pressure in the channels of the ionization gauge and the pressure variation around the payload are both decreased. The DSMC results agree very well with data predicted by compressible flow theory and free molecular theory when applicable. Comparison between the DSMC results and the TOMEX flight data shows generally good agreement.
- Published
- 2006
50. The outer radiation belt injection, transport, acceleration and loss satellite (ORBITALS): A canadian small satellite mission for ILWS
- Author
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T. P. O'Brien, Dimitris Vassiliadis, Marc Lessard, Richard M. Thorne, David J. Knudsen, Robert Rankin, Brian Fraser, David Boteler, I. Thomson, K. Balmain, R. Fedosejeves, Ian R. Mann, John R. Wygant, C. Unick, T. M. Loto'aniu, Geoffrey D. Reeves, Janet C. Green, Sebastien Bourdarie, George J. Sofko, Vania K. Jordanova, Danny Summers, Z. C. Dent, J. H. Clemmons, David K. Milling, L. M. Kistler, J. F. Fennell, A. Kale, I. J. Rae, Louis Ozeke, Aaron J. Ridley, Terrance Onsager, Andrew W. Yau, Ying Y. Tsui, J. B. Blake, and Alex Degeling
- Subjects
Physics ,Atmospheric Science ,Geosynchronous orbit ,Aerospace Engineering ,Magnetosphere ,Astronomy ,Astronomy and Astrophysics ,Space weather ,Canadian Geospace Monitoring ,Acceleration ,symbols.namesake ,Geophysics ,Space and Planetary Science ,Van Allen radiation belt ,Physics::Space Physics ,symbols ,Communications satellite ,General Earth and Planetary Sciences ,Satellite ,Astrophysics::Earth and Planetary Astrophysics - Abstract
The outer radiation belt injection, transport, acceleration and loss satellite (ORBITALS) is a small satellite mission proposed as a Canadian contribution to the satellite infrastructure for the International Living With a Star (ILWS) program. The ORBITALS will monitor the energetic electron and ion populations in the inner magnetosphere across a wide range of energies (keV to tens of MeV) as well as the dynamic electric and magnetic fields, waves and cold plasma environment which govern the injection, transport, acceleration and loss of these energetic and space weather critical particle populations. ORBITALS will be launched around 2010–2012 into a low-inclination GTO-like orbit which maximizes the long-lasting apogee-pass conjunctions with both the ground-based instruments of the Canadian Geospace Monitoring (CGSM) array as well as with the GOES East and West and geosynchronous communications satellites in the North American sector. Specifically, the ORBITALS will make the measurements necessary to gain fundamental new understanding of the relative importance of different physical acceleration and loss processes which are hypothesised to shape the energetic particle populations in the inner magnetosphere. The ORBITALS will also provide the raw radiation measurements at MEO altitudes necessary for the development of the next-generation of radiation belt specification models, and on-board experiments will also monitor the dose, single-event upset, and deep-dielectric charging responses of electronic components on-orbit. In this paper we outline the scientific objectives of the ORBITALS mission, discuss how the ORBITALS will lead to solutions to outstanding questions in inner magnetospheric science, and examine how the ORBITALS will complement other proposed inner magnetosphere missions in the ILWS era.
- Published
- 2006
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