scholarly journals Electron pitch-angle diffusion in radiation belts: The effects of whistler wave oblique propagation

2012 ◽  
Vol 39 (8) ◽  
pp. n/a-n/a ◽  
Author(s):  
A. Artemyev ◽  
O. Agapitov ◽  
H. Breuillard ◽  
V. Krasnoselskikh ◽  
G. Rolland
Keyword(s):  
Pitch Angle ◽  
Radiation Belts ◽  
Whistler Wave ◽  
Oblique Propagation

Nonlinear theory of a whistler wave

1975 ◽  
Vol 14 (3) ◽  
pp. 543-549 ◽  
Author(s):  
Takashi Yamamoto
Keyword(s):  
Growth Rate ◽  
Pitch Angle ◽  
Particle Distribution ◽  
Whistler Wave ◽  
Finite Width ◽  
Whistler Mode ◽  
Mode Spectrum ◽  
Numerical Result ◽  
Orbit Model ◽  
Resonance Function

Using the Dupree—Weinstock perturbed-orbit model of plasma turbulence, we obtain the diffusion equation describing the evolution of the average one-particle distribution function for whistler mode turbulence. The numerical result for electron pitch-angle diffusion within this scheme leads us to conclude that the effect of the resonance broadening due to perturbed orbits on the pitch-angle diffusion coefficient is not large compared with that evaluated by the unperturbed orbit in the whistler mode spectrum with a finite width. Based on the explicitly evaluated resonance function, the effects of this broadening on the growth rate for the whistler wave are also discussed.

scholarly journals POLAR spacecraft observations of helium ion angular anisotropy in the Earth's radiation belts

1999 ◽  
Vol 17 (6) ◽  
pp. 723-733 ◽  
Author(s):  
W. N. Spjeldvik ◽  
T. A. Fritz ◽  
J. Chen ◽  
R. B. Sheldon
Keyword(s):  
Local Time ◽  
Pitch Angle ◽  
Radiation Belt ◽  
Radiation Belts ◽  
Magnetic Local Time ◽  
Angle Distribution ◽  
Pitch Angle Distribution ◽  
Helium Ion ◽  
Earth’S Radiation Belt ◽  
Earth's Radiation Belts

Abstract. New observations of energetic helium ion fluxes in the Earth's radiation belts have been obtained with the CAMMICE/HIT instrument on the ISTP/GGS POLAR spacecraft during the extended geomagnetically low activity period April through October 1996. POLAR executes a high inclination trajectory that crosses over both polar cap regions and passes over the geomagnetic equator in the heart of the radiation belts. The latter attribute makes possible direct observations of nearly the full equatorial helium ion pitch angle distributions in the heart of the Earth's radiation belt region. Additionally, the spacecraft often re-encounters the same geomagnetic flux tube at a substantially off-equatorial location within a few tens of minutes prior to or after the equatorial crossing. This makes both the equatorial pitch angle distribution and an expanded view of the local off-equatorial pitch angle distribution observable. The orbit of POLAR also permitted observations to be made in conjugate magnetic local time sectors over the course of the same day, and this afforded direct comparison of observations on diametrically opposite locations in the Earth's radiation belt region at closely spaced times. Results from four helium ion data channels covering ion kinetic energies from 520 to 8200 KeV show that the distributions display trapped particle characteristics with angular flux peaks for equatorially mirroring particles as one might reasonably expect. However, the helium ion pitch angle distributions generally flattened out for equatorial pitch angles below about 45°. Significant and systematic helium ion anisotropy difference at conjugate magnetic local time were also observed, and we report quiet time azimuthal variations of the anisotropy index.Key words. Magnetospheric physics (energetic particles · trapped; magnetospheric configuration and dynamics; plasmasphere)

Pitch-angle diffusion of electrons through growing and propagating along a magnetic field electromagnetic wave in Earth's radiation belts

2015 ◽  
Vol 22 (6) ◽  
pp. 062903 ◽  
Author(s):  
C.-R. Choi ◽  
M.-H. Woo ◽  
K. Dokgo ◽  
E.-J. Choi ◽  
K.-W. Min ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Wave ◽  
Pitch Angle ◽  
Radiation Belts ◽  
Earth's Radiation Belts

Wave–particle interaction and enhanced precipitation of charged particles

1985 ◽  
Vol 63 (4) ◽  
pp. 445-452
Author(s):  
R. N. Singh ◽  
R. Prasad
Keyword(s):  
Electric Fields ◽  
Geomagnetic Field ◽  
Pitch Angle ◽  
Electron Flux ◽  
Particle Interaction ◽  
Charged Particles ◽  
Lower Ionosphere ◽  
Wave Interaction ◽  
Whistler Wave ◽  
Inhomogeneity Parameter

In addition to parallel electric fields, the distortions in the geomagnetic field have been considered in the study of resonant whistler wave interaction with gyrating charged particles. Mead axisymmetric distortions in the geomagnetic field have been considered and new expressions for the inhomogeneity parameter, αd, have been obtained. Considering the diffusion of charged particles in pitch angle, the variation in the precipitating electron flux under varying magnetospheric conditions has been computed. The variation in the distribution of trapped charged particles is shown to play an important role in controlling the electron flux precipitated into the lower ionosphere.

Effect of finite correlation time on the wave-particle interactions of nonlinear electrostatic structures with electrons in the Earth's radiation belts.

2020 ◽  
Author(s):  
Adnane Osmane
Keyword(s):  
Phase Space ◽  
Pitch Angle ◽  
Radiation Belts ◽  
Particle Interactions ◽  
Chorus Waves ◽  
Angle Scattering ◽  
Open Question ◽  
Finite Correlation ◽  
Earth's Radiation Belts

<p><em>In situ</em> measurements of electron scale fluctuations by the Van Allen Probes and MMS have demonstrated the ubiquitous occurrence of phase-space holes and various kinetic nonlinear structures in the Earth's magnetosphere. However it remains an open question whether phase-space holes have to be incorporated into global magnetospheric models describing the energisation and acceleration of electrons. In this communication we will review current wave-particle models of electron phase-space holes interacting with energetic electrons (e.g. >1 keV in the Earth's radiation belts)  and present new theoretical results showing that finite correlation times of phase-space holes results in enhanced pitch-angle scattering. The pitch-angle scattering by phase-space holes is shown to be on par with that produced by chorus waves, and in some instances outgrows the chorus contribution. </p><p> </p>

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