Home » Shprits et al. 2022

A New Population of Ultra-Relativistic Electrons in the Outer Radiation Zone

Shprits Y. Y., H. J. Allison, D. Wang, A. Drozdov, M. Szabo-Roberts, I. Zhelavskaya, R. Vasile, (2022), A New Population of Ultra-Relativistic Electrons in the Outer Radiation Zone, J. Geophys. Res. [Space Physics], 127, e2021JA030214, doi:10.1029/2021JA030214, e2021JA030214 2021JA030214

Abstract

Abstract Van Allen Probes measurements revealed the presence of the most unusual structures in the ultra-relativistic radiation belts. Detailed modeling, analysis of pitch angle distributions, analysis of the difference between relativistic and ultra-realistic electron evolution, along with theoretical studies of the scattering and wave growth, all indicate that electromagnetic ion cyclotron (EMIC) waves can produce a very efficient loss of the ultra-relativistic electrons in the heart of the radiation belts. Moreover, a detailed analysis of the profiles of phase space densities provides direct evidence for localized loss by EMIC waves. The evolution of multi-MeV fluxes shows dramatic and very sudden enhancements of electrons for selected storms. Analysis of phase space density profiles reveals that growing peaks at different values of the first invariant are formed at approximately the same radial distance from the Earth and show the sequential formation of the peaks from lower to higher energies, indicating that local energy diffusion is the dominant source of the acceleration from MeV to multi-MeV energies. Further simultaneous analysis of the background density and ultra-relativistic electron fluxes shows that the acceleration to multi-MeV energies only occurs when plasma density is significantly depleted outside of the plasmasphere, which is consistent with the modeling of acceleration due to chorus waves.

Authors (sorted by name)

Allison Drozdov Shprits Szabo-Roberts Vasile Wang Zhelavskaya

Journal / Conference

Journal Of Geophysical Research (Space Physics)

Bibtex

@article{https://doi.org/10.1029/2021JA030214,
author = {Shprits, Yuri Y. and Allison, Hayley J. and Wang, Dedong and Drozdov, Alexander and Szabo-Roberts, Matyas and Zhelavskaya, Irina and Vasile, Ruggero},
title = {A New Population of Ultra-Relativistic Electrons in the Outer Radiation Zone},
journal = {Journal of Geophysical Research: Space Physics},
volume = {127},
number = {5},
pages = {e2021JA030214},
keywords = {radiation belts, ultra-relativistic electrons, EMIC waves, modeling, plasma density, chorus waves},
doi = {https://doi.org/10.1029/2021JA030214},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2021JA030214},
eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021JA030214},
note = {e2021JA030214 2021JA030214},
abstract = {Abstract Van Allen Probes measurements revealed the presence of the most unusual structures in the ultra-relativistic radiation belts. Detailed modeling, analysis of pitch angle distributions, analysis of the difference between relativistic and ultra-realistic electron evolution, along with theoretical studies of the scattering and wave growth, all indicate that electromagnetic ion cyclotron (EMIC) waves can produce a very efficient loss of the ultra-relativistic electrons in the heart of the radiation belts. Moreover, a detailed analysis of the profiles of phase space densities provides direct evidence for localized loss by EMIC waves. The evolution of multi-MeV fluxes shows dramatic and very sudden enhancements of electrons for selected storms. Analysis of phase space density profiles reveals that growing peaks at different values of the first invariant are formed at approximately the same radial distance from the Earth and show the sequential formation of the peaks from lower to higher energies, indicating that local energy diffusion is the dominant source of the acceleration from MeV to multi-MeV energies. Further simultaneous analysis of the background density and ultra-relativistic electron fluxes shows that the acceleration to multi-MeV energies only occurs when plasma density is significantly depleted outside of the plasmasphere, which is consistent with the modeling of acceleration due to chorus waves.},
year = {2022}
}