Modeling of Magnetic Dipolarizations and Turbulence in Earth’s Magnetotail as Factors of Plasma Acceleration and Transfer

Аннотация

The paper is devoted to studying processes of plasma particle acceleration in the process of magnetic dipolarizations in a current sheet of Earth’s magnetotail. A numerical model is constructed that allows evaluation of particle acceleration in three possible scenarios: (A) Proper dipolarization; (B) Passage of multiple dipolarization fronts; (C) Passage of fronts followed by high-frequency electromagnetic oscillations. The energy spectra of three types of accelerated particles are obtained: hydrogen H⁺ and oxygen O⁺ ions and electrons e^–. It is shown that, at different time scales, predominant acceleration of various particle populations occurs in scenarios (A)–(C). Oxygen ions are accelerated most efficiently in single dipolarization process (A), protons (and, to some extent, electrons), in scenario (B), whereas scenario (C) is most efficient for acceleration of electrons. It is shown that accounting for high-frequency electromagnetic fluctuations, accompanying magnetic dipolarization, may explain the appearance of streams of particles with energies on the order of hundreds of keV in Earth’s magnetotail.