Ni B., X. Cao, Y. Y. Shprits, D. Summers, X. Gu, S. Fu, Y. Lou, (2018), Hot Plasma Effects on the Cyclotron-Resonant Pitch-Angle Scattering Rates of Radiation Belt Electrons Due to EMIC Waves, Geophysical Research Letters, 45, 21-30, doi:10.1002/2017GL076028
Abstract
Abstract To investigate the hot plasma effects on the cyclotron-resonant interactions between electromagnetic ion cyclotron (EMIC) waves and radiation belt electrons in a realistic magnetospheric environment, calculations of the wave-induced bounce-averaged pitch angle diffusion coefficients are performed using both the cold and hot plasma dispersion relations. The results demonstrate that the hot plasma effects have a pronounced influence on the electron pitch angle scattering rates due to all three EMIC emission bands (H+, He+, and O+) when the hot plasma dispersion relation deviates significantly from the cold plasma approximation. For a given wave spectrum, the modification of the dispersion relation by hot anisotropic protons can strongly increase the minimum resonant energy for electrons interacting with O+ band EMIC waves, while the minimum resonant energies for H+ and He+ bands are not greatly affected. For H+ band EMIC waves, inclusion of hot protons tends to weaken the pitch angle scattering efficiency of >5 MeV electrons. The most crucial differences introduced by the hot plasma effects occur for >3 MeV electron scattering rates by He+ band EMIC waves. Mainly due to the changes of resonant frequency and wave group velocity when the hot protons are included, the difference in scattering rates can be up to an order of magnitude, showing a strong dependence on both electron energy and equatorial pitch angle. Our study confirms the importance of including hot plasma effects in modeling the scattering of ultra-relativistic radiation belt electrons by EMIC waves.Authors (sorted by name)
Cao Fu Gu Lou Ni Shprits SummersJournal / Conference
Geophysical Research LettersAcknowledgments
The work was supported by the NSFC grants 41674163, 41474141, and 41204120 and the Hubei Province Natural Science Excellent Youth Foundation (2016CFA044). D.S. acknowledges support from a discovery grant of the Natural Sciences and Engineering Research Council of Canada. Y.Y.S. acknowledges support from EU Horizon 2020 637302 and DFG SFB 1294. No data sets are used for this study.Grants
637302 DFG SFB 1294Bibtex
@article{doi:10.1002/2017GL076028,
author = {Ni, Binbin and Cao, Xing and Shprits, Yuri Y. and Summers, Danny and Gu, Xudong and Fu, Song and Lou, Yuequn},
title = {Hot Plasma Effects on the Cyclotron-Resonant Pitch-Angle Scattering Rates of Radiation Belt Electrons Due to EMIC Waves},
journal = {Geophysical Research Letters},
volume = {45},
number = {1},
pages = {21-30},
keywords = {wave-particle interactions, EMIC waves, radiation belt electron dynamics, hot plasma dispersion relation},
doi = {10.1002/2017GL076028},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017GL076028},
eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2017GL076028},
abstract = {Abstract To investigate the hot plasma effects on the cyclotron-resonant interactions between electromagnetic ion cyclotron (EMIC) waves and radiation belt electrons in a realistic magnetospheric environment, calculations of the wave-induced bounce-averaged pitch angle diffusion coefficients are performed using both the cold and hot plasma dispersion relations. The results demonstrate that the hot plasma effects have a pronounced influence on the electron pitch angle scattering rates due to all three EMIC emission bands (H+, He+, and O+) when the hot plasma dispersion relation deviates significantly from the cold plasma approximation. For a given wave spectrum, the modification of the dispersion relation by hot anisotropic protons can strongly increase the minimum resonant energy for electrons interacting with O+ band EMIC waves, while the minimum resonant energies for H+ and He+ bands are not greatly affected. For H+ band EMIC waves, inclusion of hot protons tends to weaken the pitch angle scattering efficiency of >5 MeV electrons. The most crucial differences introduced by the hot plasma effects occur for >3 MeV electron scattering rates by He+ band EMIC waves. Mainly due to the changes of resonant frequency and wave group velocity when the hot protons are included, the difference in scattering rates can be up to an order of magnitude, showing a strong dependence on both electron energy and equatorial pitch angle. Our study confirms the importance of including hot plasma effects in modeling the scattering of ultra-relativistic radiation belt electrons by EMIC waves.},
year = {2018}
}