Pitch-angle diffusion of radiation belt electrons within the plasmasphere

Lyons, L. R.; Thorne, R. M.; Kennel, C. F.

doi:10.1029/ja077i019p03455

Cited by 725 publications

(790 citation statements)

References 27 publications

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“…The equatorial distributions have been observed to have such a shape at energies comparable to those under discussion here. Lyons et al (1972) published OGO-5 data of this type and utilized a combination of cyclotron and Landau resonances to explain enhanced scattering all along the field line.…”

Section: Discussionmentioning

confidence: 99%

VLF transmission induced slot electron precipitation

Vampola¹

1977

Geophysical Research Letters

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Analysis of electron observations in the drift and bounce loss cones of the slot region of the magnetosphere indicates that the predominant mode in which electrons in the 100 to 400 keV energy range arrive in the drift loss cone is via discrete events. These events are usually traceable back to the vicinity of a high‐power‐level VLF transmitter. No gradual buildup of electron flux, proceeding eastward from the South Atlantic Anomaly, is observed. Estimates of the loss rate due to the discrete events show that this process can result in a depletion of 50% per day of the electron flux in the slot region. The wave‐particle interaction probably occurs relatively low on the field line ( ≈ 30° to 50°) because of the relationship of particle energies and wave frequencies involved. Additional scattering of the particles near the equator, either by power‐line harmonic emissions or naturally occuring ELF hiss, may be required to transport the particles to the lower interaction region.

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Section: Discussionmentioning

confidence: 99%

VLF transmission induced slot electron precipitation

Vampola¹

1977

Geophysical Research Letters

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“…We assume that the electron distribution function satisfies the one-dimensional pitchangle diffusion equation and can be factorized into timedependent and pitch angle dependent functions [Lyons et al, 1972;Albert, 1994]. The resulting equation can be cast as a two-point boundary value problem in four variables [Albert, 1994], and solved to obtain the loss timescale, t [Meredith et al, 2006a].…”

Section: Calculation Of Electron Loss Timescalesmentioning

confidence: 99%

“…However, during major geomagnetic storms, such as the Halloween storm in 2003, the flux of relativistic electrons in the slot region increases dramatically [Baker et al, 2004], as a result of enhanced inward transport and wave acceleration Shprits et al, 2006;Thorne et al, 2007]. The enhanced flux of relativistic electrons subsequently decay to the prestorm equilibrium levels on a timescale of days to weeks, largely due to the resonant pitch angle scattering by plasmaspheric hiss [Lyons et al, 1972;Lyons and Thorne, 1973;Albert, 1994;Thorne 1998a, 1998b], although losses due to lightning-induced electron precipitation may be important at lower energies [Voss et al, 1998;Blake et al, 2001;Rodger and Clilverd, 2002]. Farther out, pitch angle scattering by plasmaspheric hiss contributes to the loss of outer radiation belt electrons during the main and recovery phases of a storm [Summers et al, 2007] and can explain the quiet time decay of outer radiation belt electrons over a wide range of energies and L shells [e.g., Meredith et al, 2006a].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2007

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[1] Energetic electrons (E > 100 keV) in the Earth's radiation belts undergo Dopplershifted 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 wave normal angles and lightning-generated whistlers do not contribute significantly to radiation belt loss. The loss timescale of 2 MeV electrons due to plasmaspheric hiss propagating at small and intermediate wave normal angles in the center of the slot region (L = 2.5) lies in the range 1-10 days, consistent with recent Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX) observations. Wave turbulence in space, which is responsible for the generation plasmaspheric hiss, thus leads to the formation of the slot region. During active periods, losses due to plasmaspheric hiss may occur on a timescale of 1 day or less for a wide range of energies, 200 keV < E < 1 MeV, in the region 3.5 < L < 4.0. Plasmaspheric hiss may thus also be a significant loss process in the inner region of the outer radiation belt during magnetically disturbed periods.Citation: Meredith, N. P., R. B. Horne, S. A. Glauert, and R. R. Anderson (2007), Slot region electron loss timescales due to plasmaspheric hiss and lightning-generated whistlers,

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“…[6] The loss time scale of radiation belt electrons have been investigated by particle measurements and quantitatively compared them with the theoretical loss time scale based on the pitch angle diffusion rate [e.g., Lyons et al, 1972;Meredith et al, 2009]. Therefore, it is possible to identify the wave modes that contribute the loss of radiation belt electrons, and it seems that this method would be useful for the estimation of loss processes of plasma sheet electrons.…”

Section: Introductionmentioning

confidence: 99%

Transport and loss of the inner plasma sheet electrons: THEMIS observations

et al. 2011

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[1] Using the electron data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft measurements from 2007 to 2009, we derived global phase space density (PSD) distributions of plasma sheet electrons (2-100 eV/nT) to examine the transport process of the electrons to the inner magnetosphere and possible loss mechanisms of plasma sheet electrons during the convective transport. The inner boundaries of the electron plasma sheet were determined by the observed global distributions and compared with the Alfvén boundaries that were calculated by the sum of the simple corotation and convection electric field models. This comparison confirms the previous results that the large-scale convection electric field controls the electron transport to the inner magnetosphere. The gradual decrease in PSD is observed from the dawn to the dayside sector, indicating the existence of some loss mechanisms in the morning sector. The loss time scales estimated from the PSD distributions were compared with the theoretical ones based on the quasi-linear diffusion theory using an empirical wave model of whistler mode chorus. We also estimated the required wave amplitudes that can explain the estimated loss time scales. It is shown that whistler mode chorus has a sufficient power to scatter the plasma sheet electrons, and the required wave amplitudes are roughly consistent with the CRRES statistical survey of the chorus wave amplitude. We suggest that the loss of plasma sheet electrons in the morning sector is mainly induced by pitch angle scattering by whistler mode chorus.

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Pitch-angle diffusion of radiation belt electrons within the plasmasphere

Cited by 725 publications

References 27 publications

VLF transmission induced slot electron precipitation

VLF transmission induced slot electron precipitation

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

Transport and loss of the inner plasma sheet electrons: THEMIS observations

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