@inproceedings{Drozdov-2023-1,
author = {Drozdov, A. Y. and Allison, H. J. and Shprits, Y. Y. and Usanova, M.E. and Wang, D. and Shiller, Q. and Saikin, A. and Jaynes, A. and Kondrashov, D},
title = {Loss and Acceleration of multi-MeV Electrons and Their Corresponding Dynamic of Phase Space Density Profiles},
booktitle = {Isradynamics 2023},
series    = {Dead Sea, Israel}, 
abstract = {The Earth’s electron outer radiation belt is populated by electrons, including energies of several MeV which are usually referred to as ultrarelativistic electrons. During geomagnetic storms, the electron fluxes exhibit irregular variations over several orders of magnitude on time scales ranging from minutes to days. The analysis of such dynamics is complicated because some variations are reversible, or adiabatic, and others are irreversible. While adiabatic changes are related to the slow changes of the ambient magnetic field, irreversible changes result from the wave-particle interaction and losses on the magnetopause boundary and into the atmosphere. Separating adiabatic and nonadiabatic changes can be achieved by inferring phase space density (PSD) as a function of three adiabatic invariants. Analysis of PSD profiles allows the identification of mechanisms responsible for non-adiabatic changes. For example, the electron acceleration mechanism leads to growing peaks in PSD, while the localized rapid losses can be visible as deepening local minima. The radial diffusion usually appears as a monotonic profile. 

The loss of multi-MeV electrons can be a combination of various processes, such as outward radial diffusion and/or electron scattering due to wave-particle interaction. The rapid loss of multi-MeV electrons is possible due to interaction with electromagnetic ion cyclotron (EMIC) waves. Such a fast localized loss leads to the production of deepening minima in the electron PSD profiles, and it can play a dominant role in the observed dropouts. Concerning the acceleration of radiation belts’ electrons, we can deduce whether local wave-particle interaction with the chorus waves is associated with the acceleration of multi-MeV electrons (i.e., growing PSD peaks).

In this study, we performed a search of multi-MeV electron flux depletions and local PSD minima using observations from Van Allen Probes and Geostationary Operational Environmental Satellite (GOES). We compared the results of the statistical analysis of the PSD minima with the diffusion model, using the Versatile Electron Radiation Belts (VERB) code. The comparative analysis shows that the observed distribution of deepening minima is reproduced in the simulation with EMIC waves, while the simulation without EMIC waves does not reveal formations of deepening minima, which significantly differs from the observations. In addition, we examined the PSD profiles during multi-MeV electron acceleration events, focusing on the change in plasma density, as varying the electron density impacts the chorus wave diffusion coefficients. },
year = {2023}
}