Modeling the Quasi‐Trapped Electron Fluxes From Cosmic Ray Albedo Neutron Decay (CRAND)

Xiang, Zheng; Li, Xinlin; Selesnick, R. S.; Temerin, M.; Ni, Binbin; Zhao, Hong; Zhang, Kun; Khoo, L. Y.

doi:10.1029/2018gl081730

Cited by 26 publications

(45 citation statements)

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“…Here we assume that the dynamics of Earth's innermost hundreds of kiloelectron‐volt electrons ( L < 1.3) are controlled by azimuthal drift, PA diffusion due to elastic collisions, energy loss from inelastic collisions, and a CRAND source. The drift‐collision‐source model, for a given L ‐shell and kinetic energy, is governed by the following equation (adding a PA diffusion term and an energy loss term to equation of Xiang et al, ),

\frac{\partial J}{\partial t} + ω_{d} \frac{\partial J}{\partial ϕ} = - \frac{\partial}{\partial E} ()(, J \frac{dE}{dt}) + \frac{1}{G_{0} ()(, α_{italiceq}) \sin ()(, 2 α_{eq})} \frac{\partial}{\partial α_{eq}} (][, G_{0} ()(, α_{italiceq}) \sin ()(, 2 α_{eq}) (⟩⟨, D_{italicαα}) \frac{\partial J}{\partial α_{eq}}) + S_{e},

…”

Section: Model Descriptionmentioning

confidence: 99%

“…where J is electron flux, ω d is the bounce‐averaged drift frequency, ϕ is the drift phase or geomagnetic longitude, and t is time. S e is the electron source rate from CRAND (Xiang et al, ):

S_{e} ≅ \frac{q_{0} φ ()(, E) v}{L^{2.7} \sin α_{eq}},

…”

Section: Model Descriptionmentioning

confidence: 99%

“…CRAND was identified as an important source of the inner proton radiation belt six decades ago (Kellogg, ; Singer, ), but not for electrons in the inner belt (Lenchek et al, ). Recently, based on energetic electrons measured by the Colorado Student Space Weather Experiment CubeSat (Li et al, , ) near the inner edge of the inner radiation belt (Li et al, ), the analysis of the energy spectrum from CRAND electrons (Zhang et al, ), and numerical simulations based on the drift‐source model (Xiang et al, ), CRAND had been demonstrated to be the main source of hundreds of kiloelectron‐volt quasi‐trapped electrons at L < 2 and L ≈ 3. These new findings suggest that CRAND must also contribute to inner belt trapped electrons, and thus, the overall contribution of CRAND to inner radiation belt electrons needs to be further investigated.…”

Section: Introductionmentioning

confidence: 99%

“…Quasi‐trapped electrons have equatorial PAs between the local BLC and the maximum BLC over all longitudes on their drift shell, while trapped electrons have PA greater than the largest BLC across all longitudes. Based on electron measurements in these three categories, drift‐diffusion models have been developed to quantify the precipitation loss of radiation belt electrons under different geomagnetic conditions (Pham et al, ; Selesnick, ; Selesnick et al, ; Tu et al, ) and a drift‐source model has been built to reproduce the quasi‐trapped electron flux from CRAND in the inner radiation belt (Xiang et al, ). Here we report that a drift‐collision‐source model is developed for the first time to quantitatively determine the roles of atmospheric collisions and CRAND in the dynamics of the inner belt electrons.…”

Section: Introductionmentioning

confidence: 99%

“…Here we report that a drift‐collision‐source model is developed for the first time to quantitatively determine the roles of atmospheric collisions and CRAND in the dynamics of the inner belt electrons. The drift‐collision‐source model is an extension of the drift‐source model (Xiang et al, ) by adding PA diffusion due to Coulomb collisions and energy loss due to Coulomb drag together with azimuthal drift and a CRAND source. The derivation of the PA diffusion coefficient and energy loss rate from atmospheric collisions and the description of the drift‐collision‐source model are given in section .…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

On Energetic Electron Dynamics During Geomagnetic Quiet Times in Earth's Inner Radiation Belt due to Atmospheric Collisional Loss and CRAND as a Source

Xiang

Temerin

et al. 2020

JGR Space Physics

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To investigate the role of atmospheric collisions and cosmic ray albedo neutron decay (CRAND) in the dynamics of energetic electrons in the Earth's inner radiation belt during geomagnetic quiet times, a drift‐collision‐source model that includes azimuthal drift, pitch angle diffusion from elastic collision, energy loss from inelastic collision, and a CRAND source is developed. In the model, the bounce‐averaged pitch angle diffusion coefficients and energy loss rates are calculated based on scattering of electrons with neutrals given by the NRLMSISE‐00 model and with ions and electrons given by International Reference Ionosphere (IRI) 2012 model. The electron source rate from CRAND follows the recently developed drift‐source model in Xiang et al. (2019). For 304‐keV quasi‐trapped electrons at L = 1.25, simulation results with CRAND show good agreement with Detection of Electro‐Magnetic Emissions Transmitted from Earthquake Regions satellite observations, confirming that CRAND is the main source for these quasi‐trapped electrons, in contrast to the previous understanding that these quasi‐trapped electrons were formed by wide‐angle scattering of the trapped populations. For trapped electrons, 153, 304, and 509 keV at L < 1.3, the simulation results with only azimuthal drift and atmospheric collisions show a much quicker decrease than observations, while simulation results including a CRAND source are generally comparable to the observations, suggesting that CRAND is an important source of trapped hundreds of kiloelectron‐volt electrons at L < 1.3 during quiet times and provides a baseline for the electron flux even during active times as well. Furthermore, these results suggest that actual radial diffusion rates in the inner belt are lower than previous estimates in which CRAND contributions were not considered.

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