scholarly journals Ring Current Proton Dynamics Driven by Wave-Particle Interactions During a Nonstorm Period

2021 ◽  
pp. 98-104
Author(s):  
Sergei V. Smolin
Keyword(s):  
Pitch Angle ◽  
Ring Current ◽  
Activity Index ◽  
Proton Flux ◽  
Angle Distribution ◽  
Particle Interactions ◽  
Pitch Angle Distribution ◽  
Ion Cyclotron ◽  
Wave Particle Interactions ◽  
Emic Waves

Modeling of pitch angle scattering of ring current protons at interaction with electromagnetic ion cyclotron waves during a nonstorm period was considered very seldom. Therefore it is used correlated observation of enhanced electromagnetic ion cyclotron (EMIC) waves and dynamic evolution of ring current proton flux collected by Cluster satellite near the location L = 4.5 during March 26–27, 2003, a nonstorm period (Dst > –10 nT). Energetic (5–30 keV) proton fluxes are found to drop rapidly (e.g., a half hour) at lower pitch angles, corresponding to intensified EMIC wave activities. As mathematical model is used the non-stationary one-dimensional pitch angle diffusion equation which allows to compute numerically density of phase space or pitch angle distribution of the charged particles in the Earth’s magnetosphere. The model depends on time t, a local pitch angle and several parameters (the mass of a particle, the energy, the McIlwain parameter, the magnetic local time or geomagnetic eastern longitude, the geomagnetic activity index, parameter of the charged particle pitch angle distribution taken for the 90 degrees pitch angle at t = 0, the lifetime due to wave–particle interactions). This model allows numerically to estimate also for different geophysical conditions a lifetime due to wave–particle interactions. It is shown, that EMIC waves can yield decrements in proton flux within 30 minutes, consistent with the observational data. The good consent is received. Comparison of results on full model for the pitch angle range from 0 up to 180 degrees and on the model for the 90 degrees pitch angle is lead. For a perpendicular differential flux of the Earth’s ring current protons very good consent with the maximal relative error approximately 3.23 % is received

scholarly journals Energy Exchange Between Electromagnetic Ion Cyclotron (EMIC) Waves and Thermal Plasma: From Theory to Observations

2021 ◽  
Vol 8 ◽  
Author(s):  
M. E. Usanova
Keyword(s):  
Thermal Plasma ◽  
Ring Current ◽  
Plasma Heating ◽  
Particle Interactions ◽  
Ion Heating ◽  
Thermal Electron ◽  
Plasma Species ◽  
Ion Cyclotron ◽  
Radiation Belt Electrons ◽  
Emic Waves

The cold plasmaspheric plasma, the ring current and the radiation belts constitute three important populations of the inner magnetosphere. The overlap region between these populations gives rise to wave-particle interactions between different plasma species and wave modes observed in the magnetosphere, in particular, electromagnetic ion cyclotron (EMIC) waves. These waves can resonantly interact with multiple particle species, being an important loss process for both ring current ions and radiation belt electrons, as well as a cold plasma heating mechanism. This mini-review will focus on the interaction between EMIC waves and cold and thermal plasma, specifically the role of EMIC waves in cold and thermal electron and ion heating. It will discuss early theoretical results in conjunction with numerical modelling and recent satellite observations, and address outstanding problems and controversies in this field.

Ultra-relativistic electron’s pitch angle distribution narrowing associated with the solar wind density enhancement

2020 ◽  
Author(s):  
Lun Xie ◽  
Ying Xiong ◽  
Suiyan Fu ◽  
Zuyin Pu
Keyword(s):  
Solar Wind ◽  
Plasma Sheet ◽  
Pitch Angle ◽  
Dense Plasma ◽  
Particle Interaction ◽  
Angle Distribution ◽  
Pitch Angle Distribution ◽  
Solar Wind Density ◽  
Wave Particle Interaction ◽  
Emic Waves

<p>Electron pitch angle distribution (PAD) is a critical parameter in the study of the dynamics of the radiation belt electrons. It is well known that solar wind pressure has an impact on the PAD of the geomagnetically trapped electrons. Using the Van Allen Probes' data, we find that the MeV electron PAD at 4.5<L*<5.5 became narrowing (PAD is mainly concentrated at 90 degree) for over three days during a prolonged enhancement of the solar wind number density on November 27-30, 2015. During that period, the EMIC waves are observed by Van Allen Probe-A and ground stations on the afternoon and dusk MLTs at L>4. Meanwile, the precipitations of tens of keV protons and MeV electrons are observed by POES satellites. Additionally, there is a growing dip in electron phase space density at L*~5, indicating a local loss caused by the wave-particle interaction. The narrowing of the electron PAD is energy-dependent and the PAD is more anisotropic for electrons with higher energy, which is consistent with the wave-particle interaction with the EMIC waves. Furthermore, previous studies have shown that high solar wind density can lead to a hot and dense plasma sheet. The inward penetration of a dense plasma-sheet down to 4 Re has been confirmed by THEMIS spacecraft. We suggest that the overlap of the plasma sheet and the plasmasphere provide a favorable condition for exciting EMIC waves and the loss of small pitch angle electrons by EMIC waves can lead to the electron PAD narrowing. </p><div> </div>

Search for low-altitude acceleration mechanisms during an auroral substorm

1968 ◽  
Vol 46 (8) ◽  
pp. 911-921 ◽  
Author(s):  
I. B. McDiarmid ◽  
E. E. Budzinski
Keyword(s):  
Pitch Angle ◽  
Magnetic Moments ◽  
Angular Distributions ◽  
Angle Distribution ◽  
Particle Interactions ◽  
Pitch Angle Distribution ◽  
Loss Cone ◽  
Black Brant ◽  
Auroral Substorm ◽  
Low Altitude

Two Black Brant rockets were fired simultaneously from Fort Churchill during an auroral substorm. Electron spectra and angular distributions were examined at altitudes up to 800 km in an attempt to observe the effects of acceleration or loss mechanisms acting on the particles at low altitudes. In particular, the variation of the pitch-angle distribution in the loss cone for electrons with energies greater than 40 keV and near 10 keV was examined as a function of altitude. It was found that the distributions within the loss cone at higher altitudes decreased more slowly with pitch angle than expected on the basis of the observed distributions at low altitudes if no forces other than the earth's magnetic field act on the particles. The discrepancy was larger for 10-keV electrons than for 40-keV electrons. It is concluded that mechanisms exist at altitudes below 800 km which can alter the magnetic moments and/or the energies of the particles. No satisfactory explanation of the observed discrepancy has been found. An attempt was made to interpret the results in terms of wave-particle interactions which could give rise to pitch-angle diffusion, but the magnetic-wave amplitude required is at least two orders of magnitude larger than observed values.

scholarly journals Storm-time electron flux precipitation in the inner radiation belt caused by wave-particle interactions

2009 ◽  
Vol 27 (4) ◽  
pp. 1669-1677 ◽  
Author(s):  
H. Tadokoro ◽  
F. Tsuchiya ◽  
Y. Miyoshi ◽  
Y. Katoh ◽  
A. Morioka ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Magnetic Storms ◽  
Transport Processes ◽  
Angle Distribution ◽  
Particle Interactions ◽  
Angle Scattering ◽  
Whistler Mode Waves ◽  
Low Altitude ◽  
Wave Particle Interactions ◽  
The Waves

Abstract. It has been believed that electrons in the inner belt do not show the dynamical variation during magnetic storms except for great magnetic storms. However, Tadokoro et al. (2007) recently disclosed that low-altitude electrons in the inner belt frequently show flux variations during storms (Storm Time inner belt Electron Enhancement at the Low altitude (STEEL)). This paper investigates a possible mechanism explaining STEEL during small and moderate storms, and shows that it is caused not by radial transport processes but by pitch angle scattering through wave-particle interactions. The waves related to wave-particle interactions are attributed to be banded whistler mode waves around 30 kHz observed in the inner magnetosphere by the Akebono satellite. The estimated pitch angle distribution based on a numerical calculation is roughly consistent with the observed results.

scholarly journals Simultaneous Observations of Electromagnetic Ion Cyclotron (EMIC) Waves and Pitch Angle Scattering During a Van Allen Probes Conjunction

2020 ◽  
Vol 125 (4) ◽  
Author(s):  
K. Sigsbee ◽  
C. A. Kletzing ◽  
J. B. Faden ◽  
A. N. Jaynes ◽  
G. D. Reeves ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Angle Scattering ◽  
Van Allen Probes ◽  
Ion Cyclotron ◽  
Emic Waves
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