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2017 
We analyze a wave event that occurred near noon between 07:03 and 07:08 UT on 23 February 2014 detected by the Van Allen Probes B spacecraft, where waves in the lower hybrid frequency range (LHFR) and electromagnetic ion cyclotron (EMIC) waves are observed to be highly correlated, with Pearson correlation coefficient of ~0.86. We assume that the correlation is the result of LHFR wave generation by the ions\textquoteright polarization drift in the electric field of the EMIC waves. To check this assumption the drift velocities of electrons and H+, He+, and O+ ions in the measured EMIC wave electric field were modeled. Then the LHFR wave linear instantaneous growth rates for plasma with these changing drift velocities and different plasma compositions were calculated. The time distribution of these growth rates, their frequency distribution, and the frequency dependence of the ratio of the LHFR wave power spectral density (PSD) parallel and perpendicular to the ambient magnetic field to the total PSD were found. These characteristics of the growth rates were compared with the corresponding characteristics of the observed LHFR activity. Reasonable agreement between these features and the strong correlation between EMIC and LHFR energy densities support the assumption that the LHFR wave generation can be caused by the ions\textquoteright polarization drift in the electric field of an EMIC wave. Khazanov, G.; Boardsen, S.; Krivorutsky, E.; Engebretson, M.; Sibeck, D.; Chen, S.; Breneman, A.; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2017 YEAR: 2017 DOI: 10.1002/2016JA022814 nonlinear phenomena; parametric processes; Van Allen Probes; wave/wave interactions 
We analyze a wave event that occurred near noon between 07:03 and 07:08 UT on 23 February 2014 detected by the Van Allen Probes B spacecraft, where waves in the lower hybrid frequency range (LHFR) and electromagnetic ion cyclotron (EMIC) waves are observed to be highly correlated, with Pearson correlation coefficient of ~0.86. We assume that the correlation is the result of LHFR wave generation by the ions\textquoteright polarization drift in the electric field of the EMIC waves. To check this assumption the drift velocities of electrons and H+, He+, and O+ ions in the measured EMIC wave electric field were modeled. Then the LHFR wave linear instantaneous growth rates for plasma with these changing drift velocities and different plasma compositions were calculated. The time distribution of these growth rates, their frequency distribution, and the frequency dependence of the ratio of the LHFR wave power spectral density (PSD) parallel and perpendicular to the ambient magnetic field to the total PSD were found. These characteristics of the growth rates were compared with the corresponding characteristics of the observed LHFR activity. Reasonable agreement between these features and the strong correlation between EMIC and LHFR energy densities support the assumption that the LHFR wave generation can be caused by the ions\textquoteright polarization drift in the electric field of an EMIC wave. Khazanov, G.; Boardsen, S.; Krivorutsky, E.; Engebretson, M.; Sibeck, D.; Chen, S.; Breneman, A.; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2017 YEAR: 2017 DOI: 10.1002/2016JA022814 nonlinear phenomena; parametric processes; Van Allen Probes; wave/wave interactions 
Spectra of keV protons related to ioncyclotron wave packets We use the FokkerPlanckKolmogorov equation to study the statistical aspects of stochastic dynamics of the radiation belt (RB) protons driven by nonlinear electromagnetic ioncyclotron (EMIC) wave packets. We obtain the spectra of keV protons scattered by these waves that show steeping near the gyroresonance, the signature of resonant waveparticle interaction that cannot be described by a simple power law. The most likely mechanism for proton precipitation events in RBs is shown to be nonlinear waveparticle interaction, namely, the scattering of RB protons into the loss cone by EMIC waves. Khazanov, K.; Sibeck, D.; Tel\textquoterightnikhin, A.; Kronberg, T.; Published by: Physics of Plasmas Published on: 01/2017 YEAR: 2017 DOI: http://dx.doi.org/10.1063/1.4973323 Diffusion; Particle precipitation; protons; Van Allen Probes; wave particle interactions; Wave power 
2015 
Electron distribution function formation in regions of diffuse aurora The precipitation of highenergy magnetospheric electrons (E \~ 600 eV\textendash10 KeV) in the diffuse aurora contributes significant energy flux into the Earth\textquoterights ionosphere. To fully understand the formation of this flux at the upper ionospheric boundary, \~700\textendash800 km, it is important to consider the coupled ionospheremagnetosphere system. In the diffuse aurora, precipitating electrons initially injected from the plasma sheet via waveparticle interaction processes degrade in the atmosphere toward lower energies and produce secondary electrons via impact ionization of the neutral atmosphere. These precipitating electrons can be additionally reflected upward from the two conjugate ionospheres, leading to a series of multiple reflections through the magnetosphere. These reflections greatly influence the initially precipitating flux at the upper ionospheric boundary (700\textendash800 km) and the resultant population of secondary electrons and electrons cascading toward lower energies. In this paper, we present the solution of the BoltzmanLandau kinetic equation that uniformly describes the entire electron distribution function in the diffuse aurora, including the affiliated production of secondary electrons (E < 600 eV) and its energy interplay in the magnetosphere and two conjugated ionospheres. This solution takes into account, for the first time, the formation of the electron distribution function in the diffuse auroral region, beginning with the primary injection of plasma sheet electrons via both electrostatic electron cyclotron harmonic waves and whistler mode chorus waves to the loss cone, and including their subsequent multiple atmospheric reflections in the two magnetically conjugated ionospheres. It is demonstrated that magnetosphereionosphere coupling is key in forming the electron distribution function in the diffuse auroral region. Khazanov, G.; Tripathi, A.; Sibeck, D.; Himwich, E.; Glocer, A.; Singhal, R.; Published by: Journal of Geophysical Research: Space Physics Published on: 11/2015 YEAR: 2015 DOI: 10.1002/2015JA021728 diffuse aurora; electron distribution; Waveparticle interaction 
2014 
Relativistic electron precipitation events driven by electromagnetic ioncyclotron waves We adopt a canonical approach to describe the stochastic motion of relativistic belt electrons and their scattering into the loss cone by nonlinear EMIC waves. The estimated rate of scattering is sufficient to account for the rate and intensity of bursty electron precipitation. This interaction is shown to result in particle scattering into the loss cone, forming \~10 s microbursts of precipitating electrons. These dynamics can account for the statistical correlations between processes of energization, pitch angle scattering, and relativistic electron precipitation events, that are manifested on large temporal scales of the order of the diffusion time \~tens of minutes. Khazanov, G.; Sibeck, D.; Tel\textquoterightnikhin, A.; Kronberg, T.; Published by: Physics of Plasmas Published on: 08/2014 YEAR: 2014 DOI: 10.1063/1.4892185 Diffusion; Electron scattering; Nonlinear waves; waveparticle interactions; Whistler waves 
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