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arXiv · 1709.09926

Charge proportional and weakly mass-dependent acceleration of different ion species in the Earth's magnetotail

F. Catapano·G. Zimbardo·S. Perri·A. Greco·D. Delcourt·A. Retino·I. J. Cohen
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Abstract

Energetic particles with energies from tens of keV to a few hundreds keV are frequently observed in the Earth's magnetotail. Here we study, by means of a test particle numerical simulation, the acceleration of different ion species (H$^{+}$, He$^{+}$, He$^{++}$, and O$^{n+}$ with $n=1$--$6$) in the presence of transient electromagnetic perturbations. All the considered ions develop power-law tails at high energies, except for O$^+$ ions. This is strongly correlated to the time that the particle spend in the current sheet. Ion acceleration is found to be proportional to the charge state, while it grows in a weaker way with the ion mass. We find that O$^{5+/6+}$ can reach energies higher than $500$ kev. These results may explain the strong oxygen acceleration observed in the magnetotail.

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F. Catapano, G. Zimbardo, S. Perri, A. Greco, D. Delcourt, A. Retino, I. J. Cohen. 2017-09-28. Charge proportional and weakly mass-dependent acceleration of different ion species in the Earth's magnetotail. https://doi.org/10.1002/2017gl075092

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