Found 938 entries in the Bibliography.

Showing entries from 851 through 900


Modeling ring current ion and electron dynamics and plasma instabilities during a high-speed stream driven storm

1] The temporal and spatial development of the ring current is evaluated during the 23\textendash26 October 2002 high-speed stream (HSS) storm, using a kinetic ring current-atmosphere interactions model with self-consistent magnetic field (RAM-SCB). The effects of nondipolar magnetic field configuration are investigated on both ring current ion and electron dynamics. As the self-consistent magnetic field is depressed at large (>4RE) radial distances on the nightside during the storm main phase, the particles\textquoteright d ...

Jordanova, V.; Welling, D.; Zaharia, S.; Chen, L.; Thorne, R.;

YEAR: 2012     DOI: 10.1029/2011JA017433

Design, Fabrication, and Testing of the Radiation Belt Storm Probes Propulsion Systems

The Radiation Belt Storm Probes spacecraft , part of NASA\textquoterights Living with a Star program, are scheduled for launch into Earth orbit in August 2012. 1,2,3 The twin spacecraft possess identical blowdown monopropellant hydrazine propulsion systems to provide spinup/spindown, precession, Delt a\textendashV, and deorbit capability. Each spacecraft manifests eight Aerojet 0.2 lbf (0.9 N) MR\textendash103G thrust ers, three ARD\ E Inconel 718 propellant tanks, and other components required to control the fl ow of propel ...

Bushman, Stewart;

YEAR: 2012     DOI: 10.2514/6.2012-4332

RBSP; Van Allen Probes

The RBSP Spacecraft Power System Design and Development

The RBSP (Radiation Belt Storm Probes) twin spacecraft are set to launch in August 2012. The spacecraft will be inserted into the highly elliptical regions of high energy particles trapped by the magnetic field of the earth. These regions are often referred to as the Van Allen Belts. The twin spacecraft will operate entirely within the radiation belts throughout their mission. Because of the intense environment of operation and to reduce cost and risk, the approach taken in the power system electronics was to use quasi conve ...

Butler, Michael; Laughery, Sean;

YEAR: 2012     DOI: 10.2514/MIECEC1210.2514/6.2012-4059

Van Allen Probes

Radiation belt 2D and 3D simulations for CIR-driven storms during Carrington Rotation 2068

As part of the International Heliospheric Year, the Whole Heliosphere Interval, Carrington Rotation 2068, from March 20 to April 16, 2008 was chosen as an internationally coordinated observing and modeling campaign. A pair of solar wind structures identified as Corotating Interaction Regions (CIR), characteristic of the declining phase of the solar cycle and solar minimum, was identified in solar wind plasma measurements from the ACE satellite. Such structures have previously been determined to be geoeffective in producing e ...

Hudson, M.; Brito, Thiago; Elkington, Scot; Kress, Brian; Li, Zhao; Wiltberger, Mike;

YEAR: 2012     DOI: 10.1016/j.jastp.2012.03.017

Magnetosphere; Modeling; Radiation belts; Solar wind

Global distribution of EMIC waves derived from THEMIS observations

[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\textendash12 RE where the ...

Min, Kyungguk; Lee, Jeongwoo; Keika, Kunihiro; Li, W.;

YEAR: 2012     DOI: 10.1029/2012JA017515

EMIC wave occurrence; EMIC waves; plasma waves; RBSP; Van Allen Probes

Radiation Belt Storm Probe Spacecraft and Impact of Environment on Spacecraft Design

NASA\textquoterights Radiation Belt Storm Probe (RBSP) is an Earth-orbiting mission scheduled to launch in September 2012 and is the next science mission in NASA\textquoterights Living with a Star Program. The RBSP mission will investigate, characterize and understand the physical dynamics of the radiation belts, and the influence of the sun on the earth\textquoterights environment, by measuring particles, electric and magnetic fields and waves that comprise the geospace. The mission is composed of two identically instrument ...

Kirby, Karen; Bushman, Stewart; Butler, Michael; Conde, Rich; Fretz, Kristen; Herrmann, Carl; Hill, Adrian; Maurer, Richard; Nichols, Richard; Ottman, Geffrey; Reid, Mark; Rogers, Gabe; Srinivasan, Dipak; Troll, John; Williams, Bruce;

YEAR: 2012     DOI: 10.1109/AERO.2012.6187020

RBSP; Van Allen Probes

Explaining sudden losses of outer radiation belt electrons during geomagnetic storms

The Van Allen radiation belts were first discovered in 1958 by the Explorer series of spacecraft1. The dynamic outer belt consists primarily of relativistic electrons trapped by the Earth\textquoterights magnetic field. Magnetospheric processes driven by the solar wind2 cause the electron flux in this belt to fluctuate substantially over timescales ranging from minutes to years3. The most dramatic of these events are known as flux \textquoterightdropouts\textquoteright and often occur during geomagnetic storms. During such a ...

Turner, Drew; Shprits, Yuri; Hartinger, Michael; Angelopoulos, Vassilis;

YEAR: 2012     DOI: 10.1038/nphys2185

Weak turbulence in the magnetosphere: Formation of whistler wave cavity by nonlinear scattering

We consider the weak turbulence of whistler waves in the in low-β inner magnetosphere of the earth. Whistler waves, originating in the ionosphere, propagate radially outward and can trigger nonlinear induced scattering by thermal electrons provided the wave energy density is large enough. Nonlinear scattering can substantially change the direction of the wave vector of whistler waves and hence the direction of energy flux with only a small change in the frequency. A portion of whistler waves return to the ionosphere with a ...

Crabtree, C.; Rudakov, L.; Ganguli, G.; Mithaiwala, M.; Galinsky, V.; Shevchenko, V.;

YEAR: 2012     DOI: 10.1063/1.3692092

Whistler waves; Magnetosphere


Radiation belt storm probes: Resolving fundamental physics with practical consequences

The fundamental processes that energize, transport, and cause the loss of charged particles operate throughout the universe at locations as diverse as magnetized planets, the solar wind, our Sun, and other stars. The same processes operate within our immediate environment, the Earth\textquoterights radiation belts. The Radiation Belt Storm Probes (RBSP) mission will provide coordinated two-spacecraft observations to obtain understanding of these fundamental processes controlling the dynamic variability of the near-Earth radi ...

Ukhorskiy, Aleksandr; Mauk, Barry; Fox, Nicola; Sibeck, David; Grebowsky, Joseph;

YEAR: 2011     DOI: 10.1016/j.jastp.2010.12.005

Radiation belts; Space weather; Van Allen Probes

Understanding relativistic electron losses with BARREL

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\textquoterights 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 ...

Millan, R.M.;

YEAR: 2011     DOI: 10.1016/j.jastp.2011.01.006

inner magnetosphere; precipitation; Radiation belts; relativistic electrons; Van Allen Probes; wave-particle interactions


Chorus wave generation near the dawnside magnetopause due to drift shell splitting of substorm-injected electrons

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\textdegreeS) Antarctic observatories in the range of 0600\textendash0900 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\textendash240 ...

Min, Kyungguk; Lee, Jeongwoo; Keika, Kunihiro;

YEAR: 2010     DOI: 10.1029/2010JA015474

chorus and substorm; electron drift; RBSP; Substorm Injections; Van Allen Probes


Analysis of Spinning Spacecraft with Wire Booms Part 1: Derivation of Nonlinear Dynamics

Algebraic expressions for the governing equations of motion are developed to describe a spinning spacecraft with flexible appendages. Two limiting cases are investigated: appendages that are self-restoring and appendages that require spacecraft motion to restore. Solar panels have sufficient root stiffness to self-restore perturbations. Radial wire antennae have little intrinsic root stiffness and require centripetal acceleration from spacecraft rotations to restore perturbations. External forces applied for attitude correct ...

Kemp, Brian; McGee, Timothy; Shankar, Uday;

YEAR: 2009     DOI: 10.2514/6.2009-6202

RBSP; Van Allen Probes

Analysis of Spinning Spacecraft with Wire Booms Part 2: Out-of-Plane Dynamics and Maneuvers

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 vari ...

McGee, Timothy; Shankar, Uday; Kemp, Brian;

YEAR: 2009     DOI: 10.2514/6.2009-6203

RBSP; Van Allen Probes

Analysis of Spinning Spacecraft with Wire Booms Part 3: Spin-Plane Dynamics, Maneuvers, and Deployment

Several science spacecraft use long wire booms as electric-field antennas and the spacecraft spins to maintain the orientation of these flexible wires. These booms account for a majority of the total spacecraft inertia while weighing only a small fraction of the total mass. The spacecraft dynamics is therefore dominated by these booms. The analysis of such spacecraft is further complicated by other flexible ap- pendages and the presence of damping in the system, both inherent in the sys- tem and from damping mechanisms delib ...

Shankar, Uday; McGee, Timothy; Kemp, Brian;

YEAR: 2009     DOI: 10.2514/6.2009-6204

RBSP; Van Allen Probes

On the loss of relativistic electrons at geosynchronous altitude: Its dependence on magnetic configurations and external conditions

[1] The present study statistically examines geosynchronous magnetic configurations and external conditions that characterize the loss of geosynchronous MeV electrons. The loss of MeV electrons often takes place during magnetospheric storms, but it also takes place without any clear storm activity. It is found that irrespective of storm activity, the day-night asymmetry of the geosynchronous H (north-south) magnetic component is pronounced during electron loss events. For the loss process, the magnitude, rather than the dura ...

Ohtani, S.; Miyoshi, Y.; Singer, H.; Weygand, J.;

YEAR: 2009     DOI: 10.1029/2008JA013391

Magnetopause Losses


Global MHD test particle simulations of solar energetic electron trapping in the Earth\textquoterights radiation belts

Test-particle trajectories are computed in fields from a global MHD magnetospheric model simulation of the 29 October 2003 Storm Commencement to investigate trapping and transport of solar energetic electrons (SEEs) in the magnetosphere during severe storms. SEEs are found to provide a source population for a newly formed belt of View the MathML source electrons in the Earth\textquoterights inner zone radiation belts, which was observed following the 29 October 2003 storm. Energy and pitch angle distributions of the new belt ...


YEAR: 2008     DOI: 10.1016/j.jastp.2008.05.018

Shock-Induced Transport. Slot Refilling and Formation of New Belts.

Radial transport in the outer radiation belt due to global magnetospheric compressions

Earth\textquoterights outer radiation belt is populated by relativistic electrons that produce a complex dynamical response to varying geomagnetic activity. One fundamental process defining global state of the belt is radial transport of electrons across their drift shells. Radial transport is induced by resonant interaction of electron drift motion with ULF oscillations of electric and magnetic fields and is commonly believed to be a diffusive process. The goal of this paper is the analysis of radial transport due to typica ...


YEAR: 2008     DOI: 10.1016/j.jastp.2008.07.018

Radial Transport

Review of modeling of losses and sources of relativistic electrons in the outer radiation belt II: Local acceleration and loss

This paper focuses on the modeling of local acceleration and loss processes in the outer radiation belt. We begin by reviewing the statistical properties of waves that violate the first and second adiabatic invariants, leading to the loss and acceleration of high energy electrons in the outer radiation belt. After a brief description of the most commonly accepted methodology for computing quasi-linear diffusion coefficients, we present pitch-angle scattering simulations by (i) plasmaspheric hiss, (ii) a combination of plasma ...


YEAR: 2008     DOI: 10.1016/j.jastp.2008.06.014

Local Acceleration due to Wave-Particle Interaction

Review of modeling of losses and sources of relativistic electrons in the outer radiation belt I: Radial transport

In this paper, we focus on the modeling of radial transport in the Earth\textquoterights outer radiation belt. A historical overview of the first observations of the radiation belts is presented, followed by a brief description of radial diffusion. We describe how resonant interactions with poloidal and toroidal components of the ULF waves can change the electron\textquoterights energy and provide radial displacements. We also present radial diffusion and guiding center simulations that show the importance of radial transpor ...


YEAR: 2008     DOI: 10.1016/j.jastp.2008.06.008

Radial Transport

Resonant drift echoes in electron phase space density produced by dayside Pc5 waves following a geomagnetic storm

[1] The interaction between relativistic, equatorially mirroring electrons and Pc5 Ultra Low Frequency (ULF) waves in the magnetosphere is investigated using a numerical MagnetoHydroDynamic (MHD) model for waves and a test-kinetic model for electron phase space density (PSD). The temporal and spatial characteristics of a ULF wave packet are constrained using ground-based observations of narrowband ULF activity following a geomagnetic storm on 24 March 1991, which occurred from 1200 to 1340 Universal Time (UT). A salient feat ...

Degeling, A.; Rankin, R.;

YEAR: 2008     DOI: 10.1029/2008JA013254

Radial Transport

Relativistic electron precipitation by EMIC waves from self-consistent global simulations

[1] We study the effect of electromagnetic ion cyclotron (EMIC) wave scattering on radiation belt electrons during the large geomagnetic storm of 21 October 2001 with minimum Dst = -187 nT. We use our global physics-based model, which solves the kinetic equation for relativistic electrons and H+, O+, and He+ ions as a function of radial distance in the equatorial plane, magnetic local time, energy, and pitch angle. The model includes time-dependent convective transport and radial diffusion and all major loss processes and is ...

Jordanova, V.; Albert, J.; Miyoshi, Y.;

YEAR: 2008     DOI: 10.1029/2008JA013239


Radiation Belt Storm Probes: The Next Generation of Space Weather Forecasting

Reeves, Geoffrey;

YEAR: 2007     DOI: 10.1029/2007SW000341

Van Allen Probes

Dynamic evolution of energetic outer zone electrons due to wave-particle interactions during storms

[1] Relativistic electrons in the outer radiation belt are subjected to pitch angle and energy diffusion by chorus, electromagnetic ion cyclotron (EMIC), and hiss waves. Using quasi-linear diffusion coefficients for cyclotron resonance with field-aligned waves, we examine whether the resonant interactions with chorus waves produce a net acceleration or loss of relativistic electrons. We also examine the effect of pitch angle scattering by EMIC and hiss waves during the main and recovery phases of a storm. The numerical simul ...

Li, W.; . Y. Shprits, Y; Thorne, R.;

YEAR: 2007     DOI: 10.1029/2007JA012368

Local Loss due to VLF/ELF/EMIC Waves

The energization of relativistic electrons in the outer Van Allen radiation belt

The origin and dynamics of the Van Allen radiation belts is one of the longest-standing questions of the space age, and one that is increasingly important for space applications as satellite systems become more sophisticated, smaller and more susceptible to radiation effects. The precise mechanism by which the Earth\textquoterights magnetosphere is able to accelerate electrons from thermal to ultrarelativistic energies (Edouble greater than0.5 MeV) has been particularly difficult to definitively resolve. The traditional expl ...

Chen, Yue; Reeves, Geoffrey; Friedel, Reiner;

YEAR: 2007     DOI: 10.1038/nphys655

Local Acceleration due to Wave-Particle Interaction

Global MHD test particle simulations of >10 MeV radiation belt electrons during storm sudden commencement

[1] Prior to 2003, there are two known cases where ultrarelativistic (≳10 MeV) electrons appeared in the Earth\textquoterights inner zone radiation belts in association with high speed interplanetary shocks: the 24 March 1991 and the less well studied 21 February 1994 storms. During the March 1991 event electrons were injected well into the inner zone on a timescale of minutes, producing a new stably trapped radiation belt population that persisted for \~10 years. More recently, at the end of solar cycle 23, a number of vi ...

Kress, B.; Hudson, M.; Looper, M.; Albert, J.; Lyon, J.; Goodrich, C.;

YEAR: 2007     DOI: 10.1029/2006JA012218

Shock-Induced Transport. Slot Refilling and Formation of New Belts.

Slot region electron loss timescales due to plasmaspheric hiss and lightning-generated whistlers

[1] Energetic electrons (E > 100 keV) in the Earth\textquoterights 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 s ...

Meredith, Nigel; Horne, Richard; Glauert, Sarah; Anderson, Roger;

YEAR: 2007     DOI: 10.1029/2007JA012413

Local Loss due to VLF/ELF/EMIC Waves

Refilling of the slot region between the inner and outer electron radiation belts during geomagnetic storms

[1] Energetic electrons (>=50 keV) are injected into the slot region (2 < L < 4) between the inner and outer radiation belts during the early recovery phase of geomagnetic storms. Enhanced convection from the plasma sheet can account for the storm-time injection at lower energies but does not explain the rapid appearance of higher-energy electrons (>=150 keV). The effectiveness of either radial diffusion (driven by enhanced ULF waves) or local acceleration (during interactions with enhanced whistler mode chorus emissions), a ...

Thorne, R.; . Y. Shprits, Y; Meredith, N.; Horne, R.; Li, W.; Lyons, L.;

YEAR: 2007     DOI: 10.1029/2006JA012176

Shock-Induced Transport. Slot Refilling and Formation of New Belts.

The effect of ULF compressional modes and field line resonances on relativistic electron dynamics

The adiabatic, drift-resonant interaction between relativistic, equatorially mirroring electrons and a ULF compressional wave that couples to a field line resonance (FLR) is modelled. Investigations are focussed on the effect of azimuthal localisation in wave amplitude on the electron dynamics. The ULF wave fields on the equatorial plane (r , φ ) are modelled using a box model [Zhu, X., Kivelson, M.G., 1988. Analytic formulation and quantitative solutions of the coupled ULF wave problem. J. Geophys. Res. 93(A8), 8602\text ...

Degeling, A.; Rankin, R.; Kabin, K.; Marchand, R.; Mann, I.R.;

YEAR: 2007     DOI: 10.1016/j.pss.2006.04.039

Radial Transport

Timescales for radiation belt electron acceleration and loss due to resonant wave-particle interactions: 1. Theory

Radiation belt electrons can interact with various modes of plasma wave in their drift orbits about the Earth, including whistler-mode chorus outside the plasmasphere, and both whistler-mode hiss and electromagnetic ion cyclotron waves inside the plasmasphere. Electrons undergo gyroresonant diffusion in their interactions with these waves. To determine the timescales for electron momentum diffusion and pitch angle diffusion, we develop bounce-averaged quasi-linear resonant diffusion coefficients for field-aligned electromagn ...

Summers, D.; Ni, Binbin; Meredith, Nigel;

YEAR: 2007     DOI: 10.1029/2006JA011801

Local Acceleration due to Wave-Particle Interaction

Review of radiation belt relativistic electron losses

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 partic ...


YEAR: 2007     DOI: 10.1016/j.jastp.2006.06.019

Local Loss due to VLF/ELF/EMIC Waves


Observation of two distinct, rapid loss mechanisms during the 20 November 2003 radiation belt dropout event

The relativistic electron dropout event on 20 November 2003 is studied using data from a number of satellites including SAMPEX, HEO, ACE, POES, and FAST. The observations suggest that the dropout may have been caused by two separate mechanisms that operate at high and low L-shells, respectively, with a separation at L \~ 5. At high L-shells (L > 5), the dropout is approximately independent of energy and consistent with losses to the magnetopause aided by the Dst effect and outward radial diffusion which can deplete relativis ...

Bortnik, J.; Thorne, R.; O\textquoterightBrien, T.; Green, J.; Strangeway, R.; . Y. Shprits, Y; Baker, D.;

YEAR: 2006     DOI: 10.1029/2006JA011802

Local Loss due to VLF/ELF/EMIC Waves

Radial diffusion and MHD particle simulations of relativistic electron transport by ULF waves in the September 1998 storm

In an MHD particle simulation of the September 1998 magnetic storm the evolution of the radiation belt electron radial flux profile appears to be diffusive, and diffusion caused by ULF waves has been invoked as the probable mechanism. In order to separate adiabatic and nonadiabatic effects and to investigate the radial diffusion mechanism during this storm, in this work we solve a radial diffusion equation with ULF wave diffusion coefficients and a time-dependent outer boundary condition, and the results are compared with th ...

Fei, Yue; Chan, Anthony; Elkington, Scot; Wiltberger, Michael;

YEAR: 2006     DOI: 10.1029/2005JA011211

Radial Transport

Outward radial diffusion driven by losses at magnetopause

Loss mechanisms responsible for the sudden depletions of the outer electron radiation belt are examined based on observations and radial diffusion modeling, with L*-derived boundary conditions. SAMPEX data for October\textendashDecember 2003 indicate that depletions often occur when the magnetopause is compressed and geomagnetic activity is high, consistent with outward radial diffusion for L* > 4 driven by loss to the magnetopause. Multichannel Highly Elliptical Orbit (HEO) satellite observations show that depletions at hig ...

. Y. Shprits, Y; Thorne, R.; Friedel, R.; Reeves, G.; Fennell, J.; Baker, D.; Kanekal, S.;

YEAR: 2006     DOI: 10.1029/2006JA011657

Magnetopause Losses

Storm time evolution of the outer radiation belt: Transport and losses

During geomagnetic storms the magnetic field of the inner magnetosphere exhibits large-scale variations over timescales from minutes to days. Being mainly controlled by the magnetic field the motion of relativistic electrons of the outer radiation belt can be highly susceptible to its variations. This paper investigates evolution of the outer belt during the 7 September 2002 storm. Evolution of electron phase space density is calculated with the use of a test-particle simulation in storm time magnetic and electric fields. Th ...

. Y. Ukhorskiy, A; Anderson, B.; Brandt, P.; Tsyganenko, N.;

YEAR: 2006     DOI: 10.1029/2006JA011690

Magnetopause Losses

Simulating radial diffusion of energetic (MeV) electrons through a model of fluctuating electric and magnetic fields

In the present work, a test particle simulation is performed in a model of analytic Ultra Low Frequency, ULF, perturbations in the electric and magnetic fields of the Earth\textquoterights magnetosphere. The goal of this work is to examine if the radial transport of energetic particles in quiet-time ULF magnetospheric perturbations of various azimuthal mode numbers can be described as a diffusive process and be approximated by theoretically derived radial diffusion coefficients. In the model realistic compressional electroma ...

Sarris, T.; Li, X.; Temerin, M.;

YEAR: 2006     DOI: 10.5194/angeo-24-2583-2006

Radial Transport

Where Are the "Killer Electrons" of the Declining Phase of Solar Cycle 23

\textquotedblleftKiller electrons,\textquotedblright enhanced fluxes of radiation belt electrons in the magnetosphere\textendashespecially those at geosynchronous orbit (GEO)\textendashwere an important space weather phenomenon during the decline to minimum of the last 11-year solar cycle (1993\textendash1995). Indeed, the fluxes of these electrons were reported at the time to have significantly influenced the incidence of anomalies on numerous spacecraft, both commercial and national defense. The incidences of spacecraft an ...

Baker, Daniel; Lanzerotti, Louis;

YEAR: 2006     DOI: 10.1029/2006SW000259

Radiation belts

Energetic outer zone electron loss timescales during low geomagnetic activity

Following enhanced magnetic activity the fluxes of energetic electrons in the Earth\textquoterights 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 ...

Meredith, Nigel; Horne, Richard; Glauert, Sarah; Thorne, Richard; Summers, D.; Albert, Jay; Anderson, Roger;

YEAR: 2006     DOI: 10.1029/2005JA011516

Local Loss due to VLF/ELF/EMIC Waves

Phase space density analysis of the outer radiation belt energetic electron dynamics

We present an analysis of the electron phase space density in the Earth\textquoterights outer radiation belt during three magnetically disturbed periods to determine the likely roles of inward radial diffusion and local acceleration in the energization of electrons to relativistic energies. During the recovery phase of the 9 October 1990 storm and the period of prolonged substorms between 11 and 16 September 1990, the relativistic electron phase space density increases substantially and peaks in the phase space density occur ...

Iles, Roger; Meredith, Nigel; Fazakerley, Andrew; Horne, Richard;

YEAR: 2006     DOI: 10.1029/2005JA011206

Local Acceleration due to Wave-Particle Interaction

A review of ULF interactions with radiation belt electrons

Energetic particle fluxes in the outer zone radiation belts can vary over orders of magnitude on a variety of timescales. Power at ULF frequencies, on the order of a few millihertz, have been associated with changes in flux levels among relativis- tic electrons comprising the outer zone of the radiation belts. Power in this part of the spectrum may occur as a result of a number of processes, including internally- generated waves induced by plasma instabilities, and externally generated processes such as shear instabilities a ...

Elkington, Scot;

YEAR: 2006     DOI: 10.1029/169GM12

Radial Transport


Impact of toroidal ULF waves on the outer radiation belt electrons

Relativistic electron fluxes in the outer radiation belt exhibit highly variable complex behavior. Previous studies have established a strong correlation of electron fluxes and the inner magnetospheric ULF waves in the Pc 3\textendash5 frequency range. Resonant interaction of ULF waves with the drift motion of radiation belt electrons violates their third adiabatic invariant and consequently leads to their radial transport. If the wave-particle interaction has a stochastic character, then the electron transport is diffusive. ...

. Y. Ukhorskiy, A; Takahashi, K; Anderson, B.; Korth, H.;

YEAR: 2005     DOI: 10.1029/2005JA011017

Radial Transport

Timescale for MeV electron microburst loss during geomagnetic storms

Energetic electrons in the outer radiation belt can resonate with intense bursts of whistler-mode chorus emission leading to microburst precipitation into the atmosphere. The timescale for removal of outer zone MeV electrons during the main phase of the October 1998 magnetic storm has been computed by comparing the rate of microburst loss observed on SAMPEX with trapped flux levels observed on Polar. Effective lifetimes are comparable to a day and are relatively independent of L shell. The lifetimes have also been evaluated ...

Thorne, R.; O\textquoterightBrien, T.; . Y. Shprits, Y; Summers, D.; Horne, R.;

YEAR: 2005     DOI: 10.1029/2004JA010882

Local Loss due to VLF/ELF/EMIC Waves

Wave acceleration of electrons in the Van Allen radiation belts

The Van Allen radiation belts1 are two regions encircling the Earth in which energetic charged particles are trapped inside the Earth\textquoterights magnetic field. Their properties vary according to solar activity2, 3 and they represent a hazard to satellites and humans in space4, 5. An important challenge has been to explain how the charged particles within these belts are accelerated to very high energies of several million electron volts. Here we show, on the basis of the analysis of a rare event where the outer radiati ...

Horne, Richard; Thorne, Richard; Shprits, Yuri; Meredith, Nigel; Glauert, Sarah; Smith, Andy; Kanekal, Shrikanth; Baker, Daniel; Engebretson, Mark; Posch, Jennifer; Spasojevic, Maria; Inan, Umran; Pickett, Jolene; Decreau, Pierrette;

YEAR: 2005     DOI: 10.1038/nature03939

Local Acceleration due to Wave-Particle Interaction

Substorm injections produce sufficient electron energization to account for MeV flux enhancements following some storms

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. Th ...

Mithaiwala, M.; Horton, W.;

YEAR: 2005     DOI: 10.1029/2004JA010511

Substorm Injections

Evaluation of quasi-linear diffusion coefficients for whistler mode waves in a plasma with arbitrary density ratio

Techniques are presented for efficiently evaluating quasi-linear diffusion coefficients for whistler mode waves propagating according to the full cold plasma index of refraction. In particular, the density ratio ωpe/Ωe can be small, which favors energy diffusion. This generalizes an approach, previously used for high-density hiss and electromagnetic ion cyclotron waves, of identifying (and omitting) ranges of wavenormal angle θ that are incompatible with cyclotron resonant frequencies ω occurring between sharp cutoffs of ...

Albert, J.;

YEAR: 2005     DOI: 10.1029/2004JA010844

Local Acceleration due to Wave-Particle Interaction

Incorporating spectral characteristics of Pc5 waves into three-dimensional radiation belt modeling and the diffusion of relativistic electrons

The influence of ultralow frequency (ULF) waves in the Pc5 frequency range on radiation belt electrons in a compressed dipole magnetic field is examined. This is the first analysis in three dimensions utilizing model ULF wave electric and magnetic fields on the guiding center trajectories of relativistic electrons. A model is developed, describing magnetic and electric fields associated with poloidal mode Pc5 ULF waves. The frequency and L dependence of the ULF wave power are included in this model by incorporating published ...

Perry, K.; Hudson, M.; Elkington, S.;

YEAR: 2005     DOI: 10.1029/2004JA010760

Radial Transport


An extreme distortion of the Van Allen belt arising from the \textquoteleftHallowe\textquoterighten\textquoteright solar storm in 2003

The Earth\textquoterights radiation belts\textemdashalso known as the Van Allen belts1\textemdashcontain high-energy electrons trapped on magnetic field lines2, 3. The centre of the outer belt is usually 20,000\textendash25,000 km from Earth. The region between the belts is normally devoid of particles2, 3, 4, and is accordingly favoured as a location for spacecraft operation because of the benign environment5. Here we report that the outer Van Allen belt was compressed dramatically by a solar storm known as the \textquotele ...

Baker, D.; Kanekal, S.; Li, X.; Monk, S.; Goldstein, J.; Burch, J.;

YEAR: 2004     DOI: 10.1038/nature03116

Shock-Induced Transport. Slot Refilling and Formation of New Belts.

Time dependent radial diffusion modeling of relativistic electrons with realistic loss rates

Model simulations are compared to the typically observed evolution of MeV electron fluxes during geomagnetic storms to investigate whether radial diffusion alone can account for the observed variability and to estimate the effect of electron lifetimes. We demonstrate that knowledge of lifetimes is crucial for understanding the radial structure of the storm-time radiation belts and their temporal evolution. Our model results suggest that outer zone lifetimes at 1 MeV are on the order of few days during quite-times and less th ...

. Y. Shprits, Y; Thorne, R.;

YEAR: 2004     DOI: 10.1029/2004GL019591

Radial Transport

Relativistic electrons in the outer radiation belt: Differentiating between acceleration mechanisms

Many theoretical models have been developed to explain the rapid acceleration to relativistic energies of electrons that form the Earth\textquoterights radiation belts. However, after decades of research, none of these models has been unambiguously confirmed by comparison to observations. Proposed models can be separated into two types: internal and external source acceleration mechanisms. Internal source acceleration mechanisms accelerate electrons already present in the inner magnetosphere (L < 6.6), while external source ...

Green, Janet; Kivelson, M.;

YEAR: 2004     DOI: 10.1029/2003JA010153

Local Acceleration due to Wave-Particle Interaction

Quantification of relativistic electron microburst losses during the GEM storms

Bursty precipitation of relativistic electrons has been implicated as a major loss process during magnetic storms. One type of precipitation, microbursts, appears to contain enough electrons to empty the prestorm outer radiation belt in approximately a day. During storms that result in high fluxes of trapped relativistic electrons, microbursts continue for several days into the recovery phase, when trapped fluxes are dramatically increasing. The present study shows that this apparent inconsistency is resolved by observations ...

O\textquoterightBrien, T.; Looper, M.; Blake, J.;

YEAR: 2004     DOI: 10.1029/2003GL018621

Local Loss due to VLF/ELF/EMIC Waves


Energization of relativistic electrons in the presence of ULF power and MeV microbursts: Evidence for dual ULF and VLF acceleration

We examine signatures of two types of waves that may be involved in the acceleration of energetic electrons in Earth\textquoterights outer radiation belts. We have compiled a database of ULF wave power from SAMNET and IMAGE ground magnetometer stations for 1987\textendash2001. Long-duration, comprehensive, in situ VLF/ELF chorus wave observations are not available, so we infer chorus wave activity from low-altitude SAMPEX observations of MeV electron microbursts for 1996\textendash2001 since microbursts are thought to be cau ...

O\textquoterightBrien, T.; Lorentzen, K.; Mann, I.; Meredith, N.; Blake, J.; Fennell, J.; Looper, M.; Milling, D.; Anderson, R.;

YEAR: 2003     DOI: 10.1029/2002JA009784

Local Acceleration due to Wave-Particle Interaction

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