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' 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' polarization drift in the electric field of an EMIC wave.
Bibliographical noteFunding Information:
Funding support for this study was provided by NASA the Van Allen Probes (formerly known as the Radiation Belt Storm Probes (RBSP)) Project, including NASA prime contract NAS5-01072, and NASA LWS Program. The data for this paper are available from George V. Khazanov at email@example.com. The EMFISIS data from the Van Allen Probes are available at http://emfisis.physics.uiowa.edu/. The Van Allen Probes EFW data are available at http://www.space.umn.edu/missions/rbspefw-home-university-of-minnesota/. OMNI data are available at the NASA/GSFC's Space Physics Data Facility's CDAWeb, at http://cdaweb.gsfc.nasa.gov/istp_public/. We acknowledge use of these data.
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- nonlinear phenomena
- parametric processes
- wave/wave interactions