Interactions between magnetosonic waves and radiation belt electrons: Comparisons of quasi‐linear calculations with test particle simulations

Li, Jinxing; Ni, Binbin; Xie, Luhua; Pu, Z. Y.; Bortnik, J.; Thorne, R. M.; Chen, Lunjin; Ma, Qianli; Fu, S. Y.; Zong, Qiugang; Wang, Xiaogang; Xiao, Chijie; Yao, Zhonghua; Guo, Ruilong

doi:10.1002/2014gl060461

Cited by 79 publications

(126 citation statements)

References 32 publications

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“…With the ðÀ1Þ lÀ1 term missing, Bortnik's formulas produce an opposite behavior of perpendicular motion, while the corrected formulas produce a result that agrees well with full particle simulation using Lorentz solver. Using the corrected formulas, Li et al 30 recently showed that the test particle simulation of interactions between magnetosonic waves and energetic electrons is in good agreement with quasilinear theory when the waves propagate enough wavelengths along the ambient magnetic field lines.…”

Section: Comparison With Bell's Equation: Sign Problemmentioning

confidence: 91%

Comparison of formulas for resonant interactions between energetic electrons and oblique whistler-mode waves

Bortnik

Xie

et al. 2015

Physics of Plasmas

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Test particle simulation is a useful method for studying both linear and nonlinear wave-particle interactions in the magnetosphere. The gyro-averaged equations of particle motion for first-order and other cyclotron harmonic resonances with oblique whistler-mode waves were first derived by Bell [J. Geophys. Res. 89, 905 (1984)] and the most recent relativistic form was given by Ginet and Albert [Phys. Fluids B 3, 2994(1991 lÀ1 term difference between their formulas of perpendicular motion for the lth-order resonance. This article presents the detailed derivation process of the generalized resonance formulas, and suggests a check of the signs for self-consistency, which is independent of the choice of conventions, that is, the energy variation equation resulting from the momentum equations should not contain any wave magnetic components, simply because the magnetic field does not contribute to changes of particle energy. In addition, we show that the wave centripetal force, which was considered small and was neglect in previous studies of nonlinear interactions, has a profound time derivative and can significantly enhance electron phase trapping especially in high frequency waves. This force can also bounce the low pitch angle particles out of the loss cone. We justify both the sign problem and the missing wave centripetal force by demonstrating wave-particle interaction examples, and comparing the gyro-averaged particle motion to the full particle motion under the Lorentz force. V C 2015 AIP Publishing LLC.

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Section: Comparison With Bell's Equation: Sign Problemmentioning

confidence: 91%

Comparison of formulas for resonant interactions between energetic electrons and oblique whistler-mode waves

Bortnik

Xie

et al. 2015

Physics of Plasmas

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“…For instance, the 8–9 October 2012 storm, the 17 March 2013 storm, and the 28–29 June 2013 storm, as denoted by the red vertical lines in Figure , occurred corresponding to the southward turning of IMF B z and the enhancement of solar wind dynamic pressure. The dynamic physics of radiation belt relativistic electrons during the first two storms, including chorus wave acceleration, ULF wave‐driven radial diffusion, scattering loss due to plasmaspheric hiss and EMIC waves, and the effects of plasmaspheric erosion/recovery and magnetopause shadowing, have been extensively studied [e.g., Reeves et al ., ; Thorne et al ., ; Shprits et al ., ; J. Li et al ., ; W. Li et al ., ; Tu et al ., ; Hudson et al ., ; Yu et al ., ; Gkioulidou et al ., ; Xiao et al ., ].…”

Section: Long‐term Poststorm Decay Of Ultrarelativistic Electron Fluxesmentioning

confidence: 99%

Variability of the pitch angle distribution of radiation belt ultrarelativistic electrons during and following intense geomagnetic storms: Van Allen Probes observations

Zou

et al. 2015

JGR Space Physics

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Fifteen months of pitch angle resolved Van Allen Probes Relativistic Electron‐Proton Telescope (REPT) measurements of differential electron flux are analyzed to investigate the characteristic variability of the pitch angle distribution of radiation belt ultrarelativistic (>2 MeV) electrons during storm conditions and during the long‐term poststorm decay. By modeling the ultrarelativistic electron pitch angle distribution as sinnα, where α is the equatorial pitch angle, we examine the spatiotemporal variations of the n value. The results show that, in general, n values increase with the level of geomagnetic activity. In principle, ultrarelativistic electrons respond to geomagnetic storms by becoming more peaked at 90° pitch angle with n values of 2–3 as a supportive signature of chorus acceleration outside the plasmasphere. High n values also exist inside the plasmasphere, being localized adjacent to the plasmapause and exhibiting energy dependence, which suggests a significant contribution from electromagnetic ion cyclotron (EMIC) wave scattering. During quiet periods, n values generally evolve to become small, i.e., 0–1. The slow and long‐term decays of the ultrarelativistic electrons after geomagnetic storms, while prominent, produce energy and L‐shell‐dependent decay time scales in association with the solar and geomagnetic activity and wave‐particle interaction processes. At lower L shells inside the plasmasphere, the decay time scales τd for electrons at REPT energies are generally larger, varying from tens of days to hundreds of days, which can be mainly attributed to the combined effect of hiss‐induced pitch angle scattering and inward radial diffusion. As L shell increases to L~3.5, a narrow region exists (with a width of ~0.5 L), where the observed ultrarelativistic electrons decay fastest, possibly resulting from efficient EMIC wave scattering. As L shell continues to increase, τd generally becomes larger again, indicating an overall slower loss process by waves at high L shells. Our investigation based upon the sinnα function fitting and the estimate of decay time scale offers a convenient and useful means to evaluate the underlying physical processes that play a role in driving the acceleration and loss of ultrarelativistic electrons and to assess their relative contributions.

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“…Natural electromagnetic emissions of equatorial noise [Russell et al, 1970;Gurnett, 1976] are receiving increased attention because of their possible importance for electron dynamics in the radiation belts [Horne et al, 2007;Li et al, 2014;Bortnik et al, 2015;Shprits, 2016;Walker et al, 2015a;Ma et al, 2016]. These emissions are composed of a complex system of many spectral lines with spacing ranging from a few hertz to a few tens of hertz, linked to ion cyclotron frequencies in local or distant sources [Gurnett, 1976;Santolík et al, 2002a;Ma et al, 2014].…”

Section: Introductionmentioning

confidence: 99%

Propagation of equatorial noise to low altitudes: Decoupling from the magnetosonic mode

Santolı́k

Parrot

Němec

2016

Geophysical Research Letters

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Equatorial noise (often phenomenologically described as magnetosonic waves in the literature) is a natural electromagnetic emission, which is generated by instability of ion distributions and which can interact with electrons in the Van Allen radiation belts. We use multicomponent electromagnetic measurements of the DEMETER spacecraft to investigate if equatorial noise propagates inward down to the Earth. Analysis of a selected event recorded under disturbed geomagnetic conditions shows that equatorial noise can be observed at an altitude of 700 km, while propagating radially downward as a superposition of spectral lines from different distant sources observed at frequencies both below and above the local proton cyclotron frequency. Changes in the local ion composition encountered by the waves during their inward propagation disconnect the identified wave mode from the low‐frequency magnetosonic mode. The local ion composition also induces a cutoff which prevents the waves from propagating down to the ground.

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Interactions between magnetosonic waves and radiation belt electrons: Comparisons of quasi‐linear calculations with test particle simulations

Cited by 79 publications

References 32 publications

Comparison of formulas for resonant interactions between energetic electrons and oblique whistler-mode waves

Comparison of formulas for resonant interactions between energetic electrons and oblique whistler-mode waves

Variability of the pitch angle distribution of radiation belt ultrarelativistic electrons during and following intense geomagnetic storms: Van Allen Probes observations

Propagation of equatorial noise to low altitudes: Decoupling from the magnetosonic mode

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