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Authors: Mauk B H
Title: Analysis of EMIC-wave-moderated flux limitation of measured energetic ion spectra in multispecies magnetospheric plasmas
Abstract: A differential Kennel-Petschek (KP) flux limit for magnetospheric energetic ions is devised taking into account multiple ion species effects on electromagnetic ion cyclotron (EMIC) waves that scatter the ions. The idea is that EMIC waves may limit the highest ion intensities during acceleration phases of storms and substorms (~ hour) while other mechanisms (e.g., charge exchange) may account for losses below those limits and over longer periods of time. This approach is applied to published Earth magnetosphere energetic ion spectra (~ keV to ~1 MeV) for radial positions (L) 3 to 6.7 RE. The flatness of the most intense spectral shapes for <100 keV indicate sculpting by just such a mechanism, but modifications of traditional KP parameters are needed to account for maximum fluxes up to 5. . .
Date: 08/2013 Publisher: Geophysical Research Letters Pages: 3804 - 3808 DOI: 10.1002/grl.50789 Available at: http://doi.wiley.com/10.1002/grl.50789
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Authors: Mauk B H, Blake J B, Baker D N, Clemmons J. H., Reeves G D, et al.
Title: The Energetic Particle Detector (EPD) Investigation and the Energetic Ion Spectrometer (EIS) for the Magnetospheric Multiscale (MMS) Mission
Abstract: The Energetic Particle Detector (EPD) Investigation is one of 5 fields-and-particles investigations on the Magnetospheric Multiscale (MMS) mission. MMS comprises 4 spacecraft flying in close formation in highly elliptical, near-Earth-equatorial orbits targeting understanding of the fundamental physics of the important physical process called magnetic reconnection using Earth’s magnetosphere as a plasma laboratory. EPD comprises two sensor types, the Energetic Ion Spectrometer (EIS) with one instrument on each of the 4 spacecraft, and the Fly’s Eye Energetic Particle Spectrometer (FEEPS) with 2 instruments on each of the 4 spacecraft. EIS measures energetic ion energy, angle and elemental compositional distributions from a required low energy limit of 20 keV for protons and 45 keV for o. . .
Date: 06/2014 Publisher: Space Science Reviews DOI: 10.1007/s11214-014-0055-5 Available at: http://link.springer.com/10.1007/s11214-014-0055-5http://link.springer.com/content/pdf/10.1007/s11214-014-0055-5
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Authors: Maurer R H, Goldsten J O, Butler M. H., and Fretz K.
Title: Five Year Results from the Engineering Radiation Monitor (ERM) and Solar Cell Monitor on the Van Allen Probes Mission
Abstract: The Engineering Radiation Monitor (ERM) measures dose, dose rate and charging currents on the Van Allen Probes mission to study the dynamics of Earth's Van Allen radiation belts. Over five years, results from this monitor show a variation in dose rates with time, a correlation between the dosimeter and charging current data and a comparison of cumulative dose to pre‐launch modeling. Solar cell degradation monitor patches track the decrease in solar array output as displacement damage accumulates. The Solar Cell Monitor shows ~33% cumulative degradation in maximum power after 5.1 years of the mission. The desire to extend the mission to ~2500 days from 800 days created increased requirements for the ionizing radiation hardness of spacecraft and science instrument electronics. We describe . . .
Date: 09/2018 Publisher: Space Weather DOI: 10.1029/2018SW001910 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW001910
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Authors: Maurer R H, and Goldsten J O
Title: The Van Allen Probes Engineering Radiation Monitor: Mission Radiation Environment and Effects
Abstract: The engineering radiation monitor (ERM) measures dose, dose rate, and charging currents on the Van Allen Probes mission to study the dynamics of Earth’s Van Allen radiation belts. Measurements from this monitor show a variation in dose rates with time, a correlation between the dosimeter and charging current data, a map of charging current versus orbit altitude, and a comparison of measured cumulative dose to prelaunch and postlaunch modeling. The measurement results and surveys of the radiation hardness for the spacecraft and science instrument electronics enable the team to predict the length of possible mission extensions. The ERM data have proved useful in investigations of two spacecraft anomalies.
Date: 07/2016 Publisher: Johns Hopkins APL Technical Digest Pages: 183-193 DOI: N/A Available at: http://www.jhuapl.edu/techdigest/TD/td3303/33_03-Maurer.pdf
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Authors: Maurer Richard, Goldsten J O, Peplowski P N, Holmes-Siedle A G, Butler Michael, et al.
Title: Early Results from the Engineering Radiation Monitor (ERM) and Solar Cell Monitor on the Van Allen Probes Mission
Abstract: The Engineering Radiation Monitor (ERM) measures dose, dose rate and charging currents on the Van Allen Probes mission to study the dynamics of earth's Van Allen radiation belts. Early results from this monitor show a variation in dose rates with time, a correlation between the dosimeter and charging current data, a map of charging current versus orbit altitude and a comparison of cumulative dose to pre-launch modeling after 260 days. Solar cell degradation monitor patches track the decrease in solar array output as displacement damage accumulates.
Date: 11/2013 Publisher: IEEE DOI: 10.1109/TNS.2013.2281937 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6651707
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Authors: Maurer Richard H., Fretz Kristin, Angert Matthew P., Bort David L., Goldsten John O., et al.
Title: Radiation-Induced Single-Event Effects on the Van Allen Probes Spacecraft
Abstract: Electronic devices on the Van Allen Probes mission have experienced more than a thousand single-event effects (SEE) during the 4.5 years of transit through the inner and outer earth trapped radiation belts. The majority of these SEE have been due to trapped protons determined by the orbit timing and the dose rate response of the engineering radiation monitor. Fault tolerant systems engineering and spacecraft operation have enabled a successful mission to date without a safe mode or spacecraft emergency.
Date: 09/2017 Publisher: IEEE Transactions on Nuclear Science Pages: 2782 - 2793 DOI: 10.1109/TNS.2017.2754878 Available at: http://ieeexplore.ieee.org/document/8047305/http://xplorestaging.ieee.org/ielx7/23/8106918/08047305.pdf?arnumber=8047305
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Authors: Maurer Richard, Goldsten John, Peplowski Patrick, Holmes-Siedle Andrew, Butler Michael, et al.
Title: Early Results From the Engineering Radiation Monitor (ERM) and Solar Cell Monitor on the Van Allen Probes Mission
Abstract: The Engineering Radiation Monitor (ERM) measures dose, dose rate and charging currents on the Van Allen Probes mission to study the dynamics of earth's Van Allen radiation belts. Early results from this monitor show a variation in dose rates with time, a correlation between the dosimeter and charging current data, a map of charging current versus orbit altitude and a comparison of cumulative dose to pre-launch modeling after 260 days. Solar cell degradation monitor patches track the decrease in solar array output as displacement damage accumulates.
Date: Jan-12-2013 Publisher: IEEE Transactions on Nuclear Science Pages: 4053 - 4058 DOI: 10.1109/TNS.2013.2281937 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6651707
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Authors: Mazur J, Friesen L, Lin A, Mabry D, Katz N, et al.
Title: The Relativistic Proton Spectrometer (RPS) for the Radiation Belt Storm Probes Mission
Abstract: 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 informati. . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 221-261 DOI: 10.1007/s11214-012-9926-9 Available at: http://link.springer.com/article/10.1007%2Fs11214-012-9926-9
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Authors: Mazur J E, O'Brien T P, Looper M D, and Blake J B
Title: Large anisotropies of >60 MeV protons throughout the inner belt observed with the Van Allen Probes mission
Abstract: We report large directional anisotropies of >60 MeV protons using instrumentation on the Van Allen Probes. The combination of a spinning satellite and measurements from the Relativistic Proton Spectrometer instruments that are insensitive to protons outside the instrument field of view together yield a new look at proton radial gradients. The relatively large proton gyroradius at 60 MeV couples with the radial gradients to produce large (maximum ~10:1) flux anisotropies depending on (i) whether the proton guiding center was above or below the Van Allen Probes spacecraft and (ii) the sign of the local flux gradient. In addition to these newly measured anisotropies, below ~2000 km we report a new effect of systematically changing minimum altitude on some proton drift shells that furthe. . .
Date: 06/2014 Publisher: Geophysical Research Letters Pages: 3738 - 3743 DOI: 10.1002/grl.v41.1110.1002/2014GL060029 Available at: http://doi.wiley.com/10.1002/grl.v41.11http://doi.wiley.com/10.1002/2014GL060029
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Authors: McCarthy Michael P., Millan Robyn M., Sample John G., and Smith David M.
Title: Radiation belt losses observed from multiple stratospheric balloons over Antarctica
Abstract: Relativistic electrons, trapped by Earth's magnetic field, have received increasing attention since increasing numbers of commercial and research spacecraft traverse regions of high radiation flux. The Van Allen probes were launched into Earth's radiation belts in September 2012, making comprehensive measurements of charged particle fluxes and electromagnetic fields, with the objective of a better understanding of the processes that modulate radiation belt fluxes. Because losses of radiation belt electrons to Earth's atmosphere are very difficult to measure from high altitude spacecraft, a balloon-based program, consisting of campaigns in January 2013 and 2014, was funded to measure losses in conjunction with the Van Allen probes mission. We present results from both balloon campaigns, whi. . .
Date: 08/2014 Publisher: IEEE DOI: 10.1109/URSIGASS.2014.6929960 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6929960
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Authors: McCollough J. P., Quinn J. M., Starks M. J., and Johnston W R
Title: Intelligent Sampling of Hazardous Particle Populations in Resource-Constrained Environments
Abstract: Sampling of anomaly-causing space environment drivers is necessary for both real-time operations and satellite design efforts, and optimizing measurement sampling helps minimize resource demands. Relating these measurements to spacecraft anomalies requires the ability to resolve spatial and temporal variability in the energetic charged particle hazard of interest. Here we describe a method for sampling particle fluxes informed by magnetospheric phenomenology so that, along a given trajectory, the variations from both temporal dynamics and spatial structure are adequately captured while minimizing oversampling. We describe the coordinates, sampling method, and specific regions and parameters employed. We compare resulting sampling cadences with data from spacecraft spanning the regions of i. . .
Date: 10/2017 Publisher: Space Weather DOI: 10.1002/2017SW001629 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017SW001629/full
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Authors: McGee Timothy G, Shankar Uday J, and Kemp Brian L
Title: Analysis of Spinning Spacecraft with Wire Booms Part 2: Out-of-Plane Dynamics and Maneuvers
Abstract: An analysis of the dynamics for a spin stabilized spacecraft consisting of a rigid central hub with four long exible wire booms is presented. The analysis focuses on the dynamics out of the spin plane of the spacecraft. Companion papers will focus on the derivations of the full nonlinear dynamics and analysis of the in plane dynamics. A linear analysis is used to estimate the mode shapes of the free response of the system, the e ects of various damping mechanisms on these modes, and the dynamic response of the system to various maneuvers. The results of an independent simulation of the full nonlinear dynamics of the system are also provided to support the linear analysis. While the dynamics and analysis approach presented can be applied to the general class of spin stabilized space. . .
Date: 08/2009 Publisher: AIAA Guidance, Navigation, and Control Conference DOI: 10.2514/6.2009-6203 Available at: http://arc.aiaa.org/doi/pdf/10.2514/6.2009-6203
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Authors: McKenna-Lawlor Susan
Title: Feasibility study of astronaut standardized career dose limits in LEO and the outlook for BLEO
Abstract: Cosmic Study Group SG 3.19/1.10 was established in February 2013 under the aegis of the International Academy of Astronautics to consider and compare the dose limits adopted by various space agencies for astronauts in Low Earth Orbit. A preliminary definition of the limits that might later be adopted by crews exploring Beyond Low Earth Orbit was, in addition, to be made. The present paper presents preliminary results of the study reported at a Symposium held in Turin by the Academy in July 2013. First, an account is provided of exposure limits assigned by various partner space agencies to those of their astronauts that work aboard the International Space Station. Then, gaps in the scientific and technical information required to safely implement human missions beyond the shielding provided. . .
Date: 11/2014 Publisher: Acta Astronautica Pages: 565 - 573 DOI: 10.1016/j.actaastro.2014.07.011 Available at: http://linkinghub.elsevier.com/retrieve/pii/S0094576514002549http://api.elsevier.com/content/article/PII:S0094576514002549?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0094576514002549?httpAccept=text/plain
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Authors: Menietti J. D., Averkamp T. F., Groene J. B., Horne R B, Shprits Y Y, et al.
Title: Survey analysis of chorus intensity at Saturn
Abstract: In order to conduct theoretical studies or modeling of pitch angle scattering of electrons by whistler mode chorus emission at Saturn, a knowledge of chorus occurrence and magnetic intensity levels, PB, as well as the distribution of PB relative to frequency and spatial parameters is essential. In this paper an extensive survey of whistler mode magnetic intensity levels at Saturn is carried out, and Gaussian fits of PB are performed. We fit the spectrum of wave magnetic intensity between the lower hybrid frequency and fceq/2 and for frequencies in the interval fceq/2 < f < 0.9 fceq, where fceq is the cyclotron frequency mapped to the equator. Saturn chorus is observed over most local times, but is dominant on the nightside in the range of 4.5 < L <7.5, with minimum power at t. . .
Date: 10/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 8415 - 8425 DOI: 10.1002/jgra.v119.1010.1002/2014JA020523 Available at: http://doi.wiley.com/10.1002/jgra.v119.10http://doi.wiley.com/10.1002/2014JA020523
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Authors: Meredith Nigel P, Horne Richard B, Glauert Sarah A, and Anderson Roger R
Title: Slot region electron loss timescales due to plasmaspheric hiss and lightning-generated whistlers
Abstract: [1] Energetic electrons (E > 100 keV) in the Earth's radiation belts undergo Doppler-shifted cyclotron resonant interactions with a variety of whistler mode waves leading to pitch angle scattering and subsequent loss to the atmosphere. In this study we assess the relative importance of plasmaspheric hiss and lightning-generated whistlers in the slot region and beyond. Electron loss timescales are determined using the Pitch Angle and energy Diffusion of Ions and Electrons (PADIE) code with global models of the spectral distributions of the wave power based on CRRES observations. Our results show that plasmaspheric hiss propagating at small and intermediate wave normal angles is a significant scattering agent in the slot region and beyond. In contrast, plasmaspheric hiss propagating at large. . .
Date: 08/2007 Publisher: Journal of Geophysical Research DOI: 10.1029/2007JA012413 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2007JA012413/abstract
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Authors: Meredith Nigel P
Title: Statistical analysis of relativistic electron energies for cyclotron resonance with EMIC waves observed on CRRES
Abstract: Electromagnetic ion cyclotron (EMIC) waves which propagate at frequencies below the proton gyrofrequency can undergo cyclotron resonant interactions with relativistic electrons in the outer radiation belt and cause pitch-angle scattering and electron loss to the atmosphere. Typical storm-time wave amplitudes of 1–10 nT cause strong diffusion scattering which may lead to significant relativistic electron loss at energies above the minimum energy for resonance, Emin. A statistical analysis of over 800 EMIC wave events observed on the CRRES spacecraft is performed to establish whether scattering can occur at geophysically interesting energies (≤2 MeV). While Emin is well above 2 MeV for the majority of these events, it can fall below 2 MeV in localized regions of high plasma density and/o. . .
Date: 06/2003 Publisher: Journal of Geophysical Research DOI: 10.1029/2002JA009700 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2002JA009700/full
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Authors: Meredith Nigel P, Cain Michelle, Horne Richard B., Thorne Richard M., Summers D., et al.
Title: Evidence for chorus-driven electron acceleration to relativistic energies from a survey of geomagnetically disturbed periods
Abstract: We perform a survey of the plasma wave and particle data from the CRRES satellite during 26 geomagnetically disturbed periods to investigate the viability of a local stochastic electron acceleration mechanism to relativistic energies driven by Doppler-shifted cyclotron resonant interactions with whistler mode chorus. Relativistic electron flux enhancements associated with moderate or strong storms may be seen over the whole outer zone (3 < L < 7), typically peaking in the range 4 < L < 5, whereas those associated with weak storms and intervals of prolonged substorm activity lacking a magnetic storm signature (PSALMSS) are typically observed further out in the regions 4 < L < 7 and 4.5 < L < 7, respectively. The most significant relativistic electron flux enhancements are seen outside of th. . .
Date: 06/2003 Publisher: Journal of Geophysical Research DOI: 10.1029/2002JA009764 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2002JA009764/abstract
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Authors: Meredith Nigel P, Horne Richard B, Glauert Sarah A, Thorne Richard M, Summers D., et al.
Title: Energetic outer zone electron loss timescales during low geomagnetic activity
Abstract: Following enhanced magnetic activity the fluxes of energetic electrons in the Earth's outer radiation belt gradually decay to quiet-time levels. We use CRRES observations to estimate the energetic electron loss timescales and to identify the principal loss mechanisms. Gradual loss of energetic electrons in the region 3.0 ≤ L ≤ 5.0 occurs during quiet periods (Kp < 3−) following enhanced magnetic activity on timescales ranging from 1.5 to 3.5 days for 214 keV electrons to 5.5 to 6.5 days for 1.09 MeV electrons. The intervals of decay are associated with large average values of the ratio fpe/fce (>7), indicating that the decay takes place in the plasmasphere. We compute loss timescales for pitch-angle scattering by plasmaspheric hiss using the PADIE code with wave properties based on C. . .
Date: 05/2006 Publisher: Journal of Geophysical Research DOI: 10.1029/2005JA011516 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2005JA011516/abstract
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Authors: Meredith Nigel P, Horne Richard B, Kersten Tobias, Li Wen, Bortnik Jacob, et al.
Title: Global model of plasmaspheric hiss from multiple satellite observations
Abstract: We present a global model of plasmaspheric hiss, using data from eight satellites, extending the coverage and improving the statistics of existing models. We use geomagnetic activity dependent templates to separate plasmaspheric hiss from chorus. In the region 22‐14 MLT the boundary between plasmaspheric hiss and chorus moves to lower L∗ values with increasing geomagnetic activity. The average wave intensity of plasmaspheric hiss is largest on the dayside and increases with increasing geomagnetic activity from midnight through dawn to dusk. Plasmaspheric hiss is most intense and spatially extended in the 200‐500 Hz frequency band during active conditions, 400 Date: 05/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025226 Available at: http://doi.wiley.com/10.1029/2018JA025226http://onlinelibrary.wiley.com/wol1/doi/10.1029/2018JA025226/fullpdfhttps://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F2018JA025226
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Authors: Meredith Nigel P, Horne Richard B, Johnstone Alan D, and Anderson Roger R
Title: The temporal evolution of electron distributions and associated wave activity following substorm injections in the inner magnetosphere
Abstract: The temporal evolution of electron distributions and associated wave activity following substorm injections in the inner magnetosphere are investigated using data from the CRRES satellite. Equatorial electron distributions and concomitant wave spectra outside the plasmapause on the nightside of the Earth are studied as a function of time since injection determined from the auroral-electrojet index (AE). The electron cyclotron harmonic (ECH) wave amplitudes are shown to be very sensitive to small modeling errors in the location of the magnetic equator. They are best understood at the ECH equator, defined by the local maximum in the ECH wave activity in the vicinity of the nominal magnetic equator, suggesting that the ECH equator is a better measure of the location of the true equator. Stron. . .
Date: 06/2000 Publisher: Journal of Geophysical Research Pages: 12907 DOI: 10.1029/2000JA900010 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2000JA900010/full
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Authors: MILLAN R, and THORNE R
Title: Review of radiation belt relativistic electron losses
Abstract: We present a brief review of radiation belt electron losses which are vitally important for controlling the dynamics of the radiation belts. A historical overview of early observations is presented, followed by a brief description of important known electron loss mechanisms. We describe key theoretical results and observations related to pitch-angle scattering by resonant interaction with plasmaspheric hiss, whistler-mode chorus and electromagnetic ion cyclotron waves, and review recent work on magnetopause losses. In particular, we attempt to organize recent observational data by loss mechanism and their relative importance to the overall rate of loss. We conclude by suggesting future observational and theoretical work that would contribute to our understanding of this important area of r. . .
Date: 03/2007 Publisher: Journal of Atmospheric and Solar-Terrestrial Physics Pages: 362 - 377 DOI: 10.1016/j.jastp.2006.06.019 Available at: http://www.sciencedirect.com/science/article/pii/S1364682606002768
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Authors: Millan R.M.
Title: Understanding relativistic electron losses with BARREL
Abstract: The primary scientific objective of the Balloon Array for RBSP Relativistic Electron Losses (BARREL) is to understand the processes responsible for scattering relativistic electrons into Earth's atmosphere. BARREL is the first Living with a Star Geospace Mission of Opportunity, and will consist of two Antarctic balloon campaigns conducted in the 2012 and 2013 Austral summer seasons. During each campaign, a total of 20 small View the MathML source(∼20kg) balloon payloads will be launched, providing multi-point measurements of electron precipitation in conjunction with in situ measurements from the two RBSP spacecraft, scheduled to launch in May 2012. In this paper we outline the scientific objectives of BARREL, highlighting a few key science questions that will be addressed by BARREL in c. . .
Date: 07/2011 Publisher: Journal of Atmospheric and Solar-Terrestrial Physics Pages: 1425 - 1434 DOI: 10.1016/j.jastp.2011.01.006 Available at: http://www.sciencedirect.com/science/article/pii/S1364682611000071
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Authors: Millan R M
Title: X-ray observations of MeV electron precipitation with a balloon-borne germanium spectrometer
Abstract: The high-resolution germanium detector aboard the MAXIS (MeV Auroral X-ray Imaging and Spectroscopy) balloon payload detected nine X-ray bursts with significant flux extending above 0.5 MeV during an 18 day flight over Antarctica. These minutes-to-hours-long events are characterized by an extremely flat spectrum (∼E−2) similar to the first MeV event discovered in 1996, indicating that the bulk of parent precipitating electrons is at relativistic energies. The MeV bursts were detected between magnetic latitudes 58°–68° (L-values of 3.8–6.7) but only in the late afternoon/dusk sectors (14:30–00:00 MLT), suggesting scattering by EMIC (electromagnetic ion cyclotron) waves as a precipitation mechanism. We estimate the average flux of precipitating E ≥ 0.5 MeV electrons to be ∼36. . .
Date: 12/2002 Publisher: Geophysical Research Letters DOI: 10.1029/2002GL015922 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2002GL015922/full
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Authors: Millan R M, McCarthy M P, Sample J G, Smith D M, Thompson L D, et al.
Title: The Balloon Array for RBSP Relativistic Electron Losses (BARREL)
Abstract: BARREL is a multiple-balloon investigation designed to study electron losses from Earth’s Radiation Belts. Selected as a NASA Living with a Star Mission of Opportunity, BARREL augments the Radiation Belt Storm Probes mission by providing measurements of relativistic electron precipitation with a pair of Antarctic balloon campaigns that will be conducted during the Austral summers (January-February) of 2013 and 2014. During each campaign, a total of 20 small (∼20 kg) stratospheric balloons will be successively launched to maintain an array of ∼5 payloads spread across ∼6 hours of magnetic local time in the region that magnetically maps to the radiation belts. Each balloon carries an X-ray spectrometer to measure the bremsstrahlung X-rays produced by precipitating relativistic electr. . .
Date: 11/2013 Publisher: Space Science Reviews DOI: 10.1007/s11214-013-9971-z Available at: http://link.springer.com/article/10.1007%2Fs11214-013-9971-z
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Authors: Min Kyungguk, Bortnik J, and Lee Jeongwoo
Title: A novel technique for rapid L∗ calculation: algorithm and implementation
Abstract: Computing the magnetic drift invariant, L*, rapidly and accurately has always been a challenge to magnetospheric modelers, especially given the im- portance of this quantity in the radiation belt community. Min et al. (2013) proposed a new method of calculating L* using the principle of energy con- servation. Continuing with the approach outlined therein, the present pa- per focuses on the technical details of the algorithm to outline the implemen- tation, systematic analysis of accuracy, and verification of the speed of the new method. We also show new improvements which enable near real-time computation of L*. The relative error is on the order of 10−3 when ∼ 0.1 RE grid resolution is used and the calculation speed is about two seconds per particle in the popular Tsyganenko. . .
Date: 05/2013 Publisher: Journal of Geophysical Research Pages: 1912-1921 DOI: 10.1002/jgra.50250 Available at: http://onlinelibrary.wiley.com/doi/10.1002/jgra.50250/full
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Authors: Min Kyungguk, Liu Kaijun, Wang Xueyi, Chen Lunjin, and Denton Richard E
Title: Fast Magnetosonic Waves Observed by Van Allen Probes: Testing Local Wave Excitation Mechanism
Abstract: Linear Vlasov theory and particle-in-cell (PIC) simulations for electromagnetic fluctuations in a homogeneous, magnetized, and collisionless plasma are used to investigate a fast magnetosonic wave event observed by the Van Allen Probes. The fluctuating magnetic field observed exhibits a series of spectral peaks at harmonics of the proton cyclotron frequency Ωp and has a dominant compressional component, which can be classified as fast magnetosonic waves. Furthermore, the simultaneously observed proton phase space density exhibits positive slopes in the perpendicular velocity space, ∂fp/∂v⊥>0, which can be a source for these waves. Linear theory analyses and PIC simulations use plasma and field parameters measured in situ except that the modeled proton distribution is modified to hav. . .
Date: 01/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024867 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024867/full
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Authors: Min Kyungguk, Bortnik J, and Lee Jeongwoo
Title: A novel technique for rapid L* calculation using UBK coordinates
Abstract: [1] The magnetic drift invariant (L*) is an important quantity used for tracking and organizing particle dynamics in the radiation belts, but its accurate calculation has been computationally expensive in the past, thus making it difficult to employ this quantity in real-time space weather applications. In this paper, we propose a new, efficient method to calculate L* using the principle of energy conservation. This method uses Whipple's (U, B, K) coordinates to quickly and accurately determine trajectories of particles at the magnetic mirror point from two-dimensional isoenergy contours. The method works for any magnetic field configuration and is able to accommodate constant electric potential along field lines. We compare the result of this method with those of International Radiation B. . .
Date: 01/2013 Publisher: Journal of Geophysical Research DOI: 10.1029/2012JA018177
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Authors: Min Kyungguk, Boardsen Scott A., Denton Richard E, and Liu Kaijun
Title: Equatorial Evolution of the Fast Magnetosonic Mode in the Source Region: Observation-Simulation Comparison of the Preferential Propagation Direction
Abstract: Recent analysis of an event observed by the Van Allen Probes in the source region outside the plasmapause has shown that fast magnetosonic waves (also referred to as equatorial noise) propagate preferentially in the azimuthal direction, implying that wave amplification should occur during azimuthal propagation. To demonstrate this, we carry out 2‐D particle‐in‐cell simulations of the fast magnetosonic mode at the dipole magnetic equator with the simulation box size, the magnetic field inhomogeneity, and the plasma parameters chosen from the same event recently analyzed. The self‐consistently evolving electric and magnetic field fluctuations are characterized by spectral peaks at harmonics of the local proton cyclotron frequency. The azimuthal component of the electric field fluctua. . .
Date: 11/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026037 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026037
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Authors: Min Kyungguk, Liu Kaijun, Bonnell John W., Breneman Aaron W., Denton Richard E, et al.
Title: Study of EMIC wave excitation using direct ion measurements
Abstract: With data from Van Allen Probes, we investigate EMIC wave excitation using simultaneously observed ion distributions. Strong He-band waves occurred while the spacecraft was moving through an enhanced density region. We extract from Helium, Oxygen, Proton, and Electron (HOPE) Mass Spectrometer measurement the velocity distributions of warm heavy ions as well as anisotropic energetic protons that drive wave growth through the ion cyclotron instability. Fitting the measured ion fluxes to multiple sinm-type distribution functions, we find that the observed ions make up about 15% of the total ions, but about 85% of them are still missing. By making legitimate estimates of the unseen cold (below ~2 eV) ion composition from cutoff frequencies suggested by the observed wave spectrum, a series of. . .
Date: 03/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020717 Available at: http://doi.wiley.com/10.1002/2014JA020717
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Authors: Min Kyungguk, Lee Jeongwoo, Keika Kunihiro, and Li W
Title: Global distribution of EMIC waves derived from THEMIS observations
Abstract: [1] Electromagnetic ion cyclotron (EMIC) waves play an important role in magnetospheric dynamics and their global distribution has been of great interest. This paper presents the distribution of EMIC waves over a broader range than ever before, as enabled by observations with the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft from 2007 to 2010. Our major findings are: (1) There are two major peaks in the EMIC wave occurrence probability. One is at dusk and 8–12 RE where the helium band dominates the hydrogen band waves. The other is at dawn and 10–12 RE where the hydrogen band dominates the helium band waves. (2) In terms of wave spectral power the dusk events are stronger (≈10 nT2/Hz) than the dawn events (≈3 nT2/Hz). (3) The dawn . . .
Date: 05/2012 Publisher: Journal of Geophysical Research DOI: 10.1029/2012JA017515
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Authors: Min Kyungguk, Takahashi Kazue, Ukhorskiy Aleksandr Y., Manweiler Jerry W., Spence Harlan E., et al.
Title: Second harmonic poloidal waves observed by Van Allen Probes in the dusk-midnight sector
Abstract: This paper presents observations of ultralow-frequency (ULF) waves from Van Allen Probes. The event that generated the ULF waves occurred 2 days after a minor geomagnetic storm during a geomagnetically quiet time. Narrowband pulsations with a frequency of about 7 mHz with moderate amplitudes were registered in the premidnight sector when Probe A was passing through an enhanced density region near geosynchronous orbit. Probe B, which passed through the region earlier, did not detect the narrowband pulsations but only broadband noise. Despite the single-spacecraft measurements, we were able to determine various wave properties. We find that (1) the observed waves are a second harmonic poloidal mode propagating westward with an azimuthal wave number estimated to be ∼100; (2) the magnetic fi. . .
Date: 03/2017 Publisher: Journal of Geophysical Research: Space Physics Pages: 3013-3-39 DOI: 10.1002/2016JA023770 Available at: onlinelibrary.wiley.com/doi/10.1002/2016JA023770/full
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Authors: Min Kyungguk, Lee Jeongwoo, and Keika Kunihiro
Title: Chorus wave generation near the dawnside magnetopause due to drift shell splitting of substorm-injected electrons
Abstract: We study the relationship between the electron injection and the chorus waves during a substorm event on 23 March 2007. The chorus waves were detected at high geomagnetic latitude (∼70°S) Antarctic observatories in the range of 0600–0900 h in magnetic local time (MLT). Electrons drifting from the injection event were measured by two LANL spacecraft at 0300 and 0900 MLT. The mapping of auroral brightening areas to the magnetic equator shows that the injection occurred in an MLT range of 2200–2400. This estimate is consistent with observations by the THEMIS A, B, and D spacecraft (which were located at 2100 MLT and did not observe electron injections). Our backward model tracing from the magnetic equator near the dawnside magnetopause (which magnetically connects to the Antar. . .
Date: 10/2010 Publisher: American Geophysical Union DOI: 10.1029/2010JA015474
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Authors: Min Kyungguk, Takahashi Kazue, Ukhorskiy Aleksandr Y., Manweiler Jerry W., Spence Harlan E., et al.
Title: Second harmonic poloidal waves observed by Van Allen Probes in the dusk-midnight sector
Abstract: This paper presents observations of ultra-low frequency (ULF) waves from Van Allen Probes. The event that generated the ULF waves occurred two days after a minor geomagnetic storm during a geomagnetically quiet time. Narrowband pulsations with a frequency of about 7 mHz with moderate amplitudes were registered in the pre-midnight sector when Probe A was passing through an enhanced density region near geosynchronous orbit. Probe B, which passed through the region earlier, did not detect the narrowband pulsations but only broadband noise. Despite the single-spacecraft measurements, we were able to determine various wave properties. We find that (1) the observed waves are a second harmonic poloidal mode propagating westward with an azimuthal wave number estimated to be ∼100; (2) the magneti. . .
Date: 02/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023770 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023770/full
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Authors: Min Kyungguk, Denton Richard E, Liu Kaijun, Gary Peter, and Spence Harlan E.
Title: Ion Bernstein instability as a possible source for oxygen ion cyclotron harmonic waves
Abstract: This paper demonstrates that an ion Bernstein instability can be a possible source for recently reported electromagnetic waves with frequencies at or near the singly ionized oxygen ion cyclotron frequency, inline image, and its harmonics. The particle measurements during strong wave activity revealed a relatively high concentration of oxygen ions (∼15%) whose phase space density exhibits a local peak at energy ∼20 keV. Given that the electron plasma-to-cyclotron frequency ratio is inline image, this energy corresponds to the particle speed inline image, where vA is the oxygen Alfvén speed. Using the observational key plasma parameters, a simplified ion velocity distribution is constructed, where the local peak in the oxygen ion velocity distribution is represented by an isotropic s. . .
Date: 05/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA023979 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA023979/full
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Authors: Mitani K., Seki K., Keika K, Gkioulidou M., Lanzerotti L J, et al.
Title: Statistical Study of Selective Oxygen Increase in High‐Energy Ring Current Ions During Magnetic Storms
Abstract: Ion transport from the plasma sheet to the ring current is the main cause of the development of the ring current. Energetic (>150 keV) ring current ions are known to be transported diffusively in several days. A recent study suggested that energetic oxygen ions are transported closer to the Earth than protons due to the diffusive transport caused by a combination of the drift and drift‐bounce resonances with Pc 3–5 ultralow frequency waves during the 24 April 2013 magnetic storm. To understand the occurrence conditions of such selective oxygen increase (SOI), we investigate the phase space densities (PSDs) between protons and oxygen ions with the first adiabatic invariants (μ) of 0.1–2.0 keV/nT measured by the Radiation Belt Storm Probes Ion Composition Experiment instrument on the . . .
Date: 04/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026168 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026168
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Authors: Mitani K., Seki K., Keika K, Gkioulidou M., Lanzerotti L J, et al.
Title: Radial Transport of Higher-Energy Oxygen Ions Into the Deep Inner Magnetosphere Observed by Van Allen Probes
Abstract: The transport mechanism of the ring current ions differs among ion energies. Lower‐energy (≲150 keV) ions are well known to be transported convectively. Higher‐energy (≳150 keV) protons are reported to be transported diffusively, while there are few reports about transport of higher‐energy oxygen ions. We report the radial transport of higher‐energy oxygen ions into the deep inner magnetosphere during the late main phase of the magnetic storm on 23–25 April 2013 observed by the Van Allen Probes spacecraft. An enhancement of 1–100 mHz magnetic fluctuations is simultaneously observed. Observations of 3 and 30 mHz geomagnetic pulsations indicate the azimuthal mode number is ≤10. The fluctuations can resonate with the drift and bounce motions of the oxygen ions. The results s. . .
Date: 05/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL077500 Available at: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL077500
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Authors: Mitchell D G, Lanzerotti L J, Kim C K, Stokes M, Ho G, et al.
Title: Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE)
Abstract: The Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) on the two Van Allen Probes spacecraft is the magnetosphere ring current instrument that will provide data for answering the three over-arching questions for the Van Allen Probes Program: RBSPICE will determine “how space weather creates the storm-time ring current around Earth, how that ring current supplies and supports the creation of the radiation belt populations,” and how the ring current is involved in radiation belt losses. RBSPICE is a time-of-flight versus total energy instrument that measures ions over the energy range from ∼20 keV to ∼1 MeV. RBSPICE will also measure electrons over the energy range ∼25 keV to ∼1 MeV in order to provide instrument background information in the radiation belts. A des. . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 263-308 DOI: 10.1007/s11214-013-9965-x Available at: http://link.springer.com/article/10.1007%2Fs11214-013-9965-x
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Authors: Mithaiwala M J, and Horton W.
Title: Substorm injections produce sufficient electron energization to account for MeV flux enhancements following some storms
Abstract: One of the main questions concerning radiation belt research is the origin of very high energy (>1 MeV) electrons following many space storms. Under the hypothesis that the plasma sheet electron population is the source of these electrons, which are convected to the outer radiation belt region during substorms, we estimate the flux of particles generated at geosynchronous orbit. We use the test particle method of following guiding center electrons as they drift in the electromagnetic fields during substorm dipolarization. The dipolarization pulse model electromagnetic fields are taken from the Li et al. (1998) substorm particle injection model. We find that a substorm dipolarization can produce enough electrons within geosynchronous orbit to account for the electrons seen following storms.. . .
Date: 07/2005 Publisher: Journal of Geophysical Research DOI: 10.1029/2004JA010511 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2004JA010511/abstract
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Authors: Miyoshi Y, Matsuda S., Kurita S., Nomura K., Keika K, et al.
Title: EMIC waves converted from equatorial noise due to M/Q=2 ions in the plasmasphere: Observations from Van Allen Probes and Arase
Abstract: Equatorial noise (EN) emissions are observed inside and outside the plasmapause. EN emissions are referred to as magnetosonic mode waves. Using data from Van Allen Probes and Arase, we found conversion from EN emissions to electromagnetic ion cyclotron (EMIC) waves in the plasmasphere and in the topside ionosphere. A low frequency part of EN emissions becomes EMIC waves through branch splitting of EN emissions, and the mode conversion from EN to EMIC waves occurs around the frequency of M/Q=2 (deuteron and/or alpha particles) cyclotron frequency. These processes result in plasmaspheric EMIC waves. We investigated the ion composition ratio by characteristic frequencies of EN emissions and EMIC waves and obtained ion composition ratios. We found that the maximum composition ratio of M/Q=2 io. . .
Date: 04/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL083024 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083024
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Authors: Miyoshi Y, Oyama S., Saito S., Kurita S., Fujiwara H., et al.
Title: Energetic electron precipitation associated with pulsating aurora: EISCAT and Van Allen Probe observations
Abstract: Pulsating auroras show quasi-periodic intensity modulations caused by the precipitation of energetic electrons of the order of tens of keV. It is expected theoretically that not only these electrons but also sub-relativistic/relativistic electrons precipitate simultaneously into the ionosphere owing to whistler-mode wave–particle interactions. The height-resolved electron density profile was observed with the European Incoherent Scatter (EISCAT) Tromsø VHF radar on 17 November 2012. Electron density enhancements were clearly identified at altitudes >68 km in association with the pulsating aurora, suggesting precipitation of electrons with a broadband energy range from ~10 keV up to at least 200 keV. The riometer and network of subionospheric radio wave observations also showed the energ. . .
Date: 03/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020690 Available at: http://doi.wiley.com/10.1002/2014JA020690
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Authors: Miyoshi Yoshizumi
Title: Rebuilding process of the outer radiation belt during the 3 November 1993 magnetic storm: NOAA and Exos-D observations
Abstract: Using the data from the NOAA and Exos-D satellites during the 3 November 1993 magnetic storm, the dynamic behavior of electrons with energies from a few tens of kiloelectronvolts to a few and its relation to plasma waves were examined. After the late main phase, relativistic electron flux started to recover from the heart of the outer radiation belt, where the cold plasma density was extremely low, and intense whistler mode chorus emissions were detected. The phase space density showed a peak in the outer belt, and the peak increased gradually. The simulation of the inward radial diffusion process could not reproduce the observed energy spectrum and phase space density variation. On the other hand, the simulated energy diffusion due to the gyroresonant electron-whistler mode wave interacti. . .
Date: 03/2003 Publisher: Journal of Geophysical Research Pages: SMP 3-1–SMP 3-15 DOI: 10.1029/2001JA007542 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2001JA007542/abstract
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Authors: Morley S. K., Henderson M G, Reeves G D, Friedel R H W, and Baker D N
Title: Phase Space Density matching of relativistic electrons using the Van Allen Probes: REPT results
Abstract: 1] Phase Space Density (PSD) matching can be used to identify the presence of nonadiabatic processes, evaluate accuracy of magnetic field models, or to cross-calibrate instruments. Calculating PSD in adiabatic invariant coordinates requires a global specification of the magnetic field. For a well specified global magnetic field, nonadiabatic processes or inadequate cross calibration will give a poor PSD match. We have calculated PSD(μ, K) for both Van Allen Probes using a range of models and compare these PSDs at conjunctions in L* (for given μ, K). We quantitatively assess the relative goodness of each model for radiation belt applications. We also quantify the uncertainty in the model magnetic field magnitude and the related uncertainties in PSD, which has applications for modeling and. . .
Date: 09/2013 Publisher: Geophysical Research Letters Pages: 4798–4802 DOI: 10.1002/grl.50909 Available at: http://doi.wiley.com/10.1002/grl.50909
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Authors: Morley Steven K., Sullivan John P., Henderson Michael G., Blake Bernard, and Baker Daniel N
Title: The Global Positioning System constellation as a space weather monitor: Comparison of electron measurements with Van Allen Probes data
Abstract: Energetic electron observations in Earth's radiation belts are typically sparse and multi-point 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. . .
Date: 02/2016 Publisher: Space Weather DOI: 10.1002/2015SW001339 Available at: http://doi.wiley.com/10.1002/2015SW001339
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Authors: Motoba Tetsuo, Takahashi Kazue, Rodriguez Juan V., and Russell Christopher T.
Title: Giant pulsations on the afternoonside: Geostationary satellite and ground observations
Abstract: Giant pulsations (Pgs) are a special class of oscillations recognized in ground magnetometer records as exhibiting highly regular sinusoidal waveforms in the east-west component with periods around 100s. Previous statistical studies showed that Pgs occur almost exclusively on the morningside with peak occurrence in the postmidnight sector. In this paper, we present observations of Pgs extending to the afternoonside, using data from the GOES13 and 15 geostationary satellites and multiple ground magnetometers located in North America. For a long-lasting event on 29 February 2012, which spanned ∼08–18h magnetic local time, we show that basic Pg properties did not change with the local time, although the period of the pulsations was longer at later local time due to increasing mass loading. . .
Date: 10/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: 8350 - 8367 DOI: 10.1002/2015JA021592 Available at: http://doi.wiley.com/10.1002/2015JA021592http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021592
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Authors: Motoba T., Takahashi K., Ukhorskiy A., Gkioulidou M., Mitchell D G, et al.
Title: Link between pre-midnight second harmonic poloidal waves and auroral undulations: Conjugate observations with a Van Allen Probes spacecraft and a THEMIS all-sky imager
Abstract: We report, for the first time, an auroral undulation event on 1 May 2013 observed by an all-sky imager (ASI) at Athabasca (L = 4.6), Canada, for which in situ field and particle measurements in the conjugate magnetosphere were available from a Van Allen Probes spacecraft. The ASI observed a train of auroral undulation structures emerging spontaneously in the pre-midnight subauroral ionosphere, during the growth phase of a substorm. The undulations had an azimuthal wavelength of ~180 km and propagated westward at a speed of 3–4 km s−1. The successive passage over an observing point yielded quasi-periodic oscillations in diffuse auroral emissions with a period of ~40 s. The azimuthal wave number m of the auroral luminosity oscillations was found to be m ~ −103. During the event the spa. . .
Date: 02/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020863 Available at: http://doi.wiley.com/10.1002/2014JA020863
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Authors: Motoba T., Ohtani S, Anderson B J, Korth H., Mitchell D., et al.
Title: On the formation and origin of substorm growth phase/onset auroral arcs inferred from conjugate space-ground observations
Abstract: Magnetotail processes and structures related to substorm growth phase/onset auroral arcs remain poorly understood mostly due to the lack of adequate observations. In this study we make a comparison between ground-based optical measurements of the premidnight growth phase/onset arcs at subauroral latitudes and magnetically conjugate measurements made by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) at ~780 km in altitude and by the Van Allen Probe B (RBSP-B) spacecraft crossing L values of ~5.0–5.6 in the premidnight inner tail region. The conjugate observations offer a unique opportunity to examine the detailed features of the arc location relative to large-scale Birkeland currents and of the magnetospheric counterpart. Our main findings include (1. . .
Date: 10/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: 8707 - 8722 DOI: 10.1002/jgra.v120.1010.1002/2015JA021676 Available at: http://doi.wiley.com/10.1002/jgra.v120.10http://doi.wiley.com/10.1002/2015JA021676http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021676
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Authors: Motoba T., Ohtani S, Gkioulidou M., Ukhorskiy A., Mitchell D G, et al.
Title: Response of Different Ion Species to Local Magnetic Dipolarization Inside Geosynchronous Orbit
Abstract: This paper examines how hydrogen, helium and oxygen (H, He and O) ion fluxes at 1–1000 keV typically respond to local magnetic dipolarization inside geosynchronous orbit (GEO). We extracted 144 dipolarizations which occurred at magnetic inclination > 30° from the 2012–2016 tail seasons' observations of the Van Allen Probes spacecraft and then defined typical flux changes of these ion species by performing a superposed epoch analysis. On average, the dipolarization inside GEO is accompanied by a precursory transient decrease in the northward magnetic field component, transient impulsive enhancement in the westward electric field component, and decrease (increase) in the proton density (temperature). The coincident ion species experience an energy‐dependent flux change, consisting of . . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025557 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025557
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Authors: Mourenas D., Zhang X.-J., Artemyev A. V., Angelopoulos V, Thorne R M, et al.
Title: Electron nonlinear resonant interaction with short and intense parallel chorus wave-packets
Abstract: One of the major drivers of radiation belt dynamics, electron resonant interaction with whistler‐mode chorus waves, is traditionally described using the quasi‐linear diffusion approximation. Such a description satisfactorily explains many observed phenomena, but its applicability can be justified only for sufficiently low intensity, long duration waves. Recent spacecraft observations of a large number of very intense lower band chorus waves (with magnetic field amplitudes sometimes reaching ∼1% of the background) therefore challenge this traditional description, and call for an alternative approach when addressing the global, long‐term effects of the nonlinear interaction of these waves with radiation belt electrons. In this paper, we first use observations from the Van Allen Probe. . .
Date: 05/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025417 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025417
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Authors: Mourenas D., Artemyev A. V., and Agapitov O.V.
Title: Approximate analytical formulation of radial diffusion and whistler-induced losses from a pre-existing flux peak in the plasmasphere
Abstract: Modeling the spatio-temporal evolution of relativistic electron fluxes trapped in the Earth's radiation belts in the presence of radial diffusion coupled with wave-induced losses should address one important question: how deep can relativistic electrons penetrate into the inner magnetosphere? However, a full modelling requires extensive numerical simulations solving the comprehensive quasi-linear equations describing pitch-angle and radial diffusion of the electron distribution, making it rather difficult to perform parametric studies of the flux behavior. Here, we consider the particular situation where a localized flux peak (or storage ring) has been produced at low L < 4 during a period of strong disturbances, through a combination of chorus-induced energy diffusion (or direct injection. . .
Date: 08/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021623 Available at: http://doi.wiley.com/10.1002/2015JA021623
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Authors: Mourenas D., Artemyev A. V., Agapitov O. V., Krasnoselskikh V., and Mozer F.S.
Title: Very Oblique Whistler Generation By Low Energy Electron Streams
Abstract: Whistler-mode chorus waves are present throughout the Earth's outer radiation belt as well as at larger distances from our planet. While the generation mechanisms of parallel lower-band chorus waves and oblique upper-band chorus waves have been identified and checked in various instances, the statistically significant presence in recent satellite observations of very oblique lower-band chorus waves near the resonance cone angle remains to be explained. Here we discuss two possible generation mechanisms for such waves. The first one is based on Landau resonance with sporadic very low energy (<4 keV) electron beams either injected from the plasmasheet or produced in situ. The second one relies on cyclotron resonance with low energy electron streams, such that their velocity distribution poss. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021135 Available at: http://doi.wiley.com/10.1002/2015JA021135
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