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Parkhomenko, Elena Igorevna; Malova, Helmi Vitalevna; Grigorenko, Elena Evgenevna; Popov, Victor Yurevich; Petrukovich, Anatolii Alekseevich; Delcourt, Dominique C.; Kronberg, Elena Aleksandrovna; Daly, Patric W.; Zelenyi, Lev Matveevich (2018): Plasma Acceleration On Multiscale Temporal Variations Of Electric And Magnetic Fields During Substorm Dipolarization In The Earth's Magnetotail. In: Annals of Geophysics, Vol. 61, No. 3, GM334
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Abstract

Magnetic field dipolarizations are often observed in the magnetotail during substornis. These generally include three temporal scales: (1) actual dipolarization when the normal magnetic field changes during several minutes from minimum to maximum level;(2) sharp B-z bursts (pulses) interpreted as the passage of multiple dipolarization fronts with characteristic time scales < 1 min, and (3) bursts of electric and magnetic fluctuations with frequencies up to electron gyrofrequency occurring at the smallest tune scales (<= 1 s). We present a numerical model where the contributions of the above processes (1)-(3) in particle acceleration are analyzed. It is shown that these processes have a resonant character at different temporal scales. While O+ ions are more likely accelerated due to the mechanism (1), H+ ions (and to some extent electrons) are effectively accelerated due to the second mechanism. High-frequency electric and magnetic fluctuations accompanying magnetic dipolarization as in (3) are also found to efficiently accelerate electrons.