On the response of quasi-adiabatic ions to magnetotail reconfigurations

Delcourt, D.C.; Malova, H.V.; Zelenyi, L.M.

Авторы: Delcourt D.C., Malova H.V., Zelenyi L.M.
Журнал: Annales Geophysicae
Том: 35
Номер: 1
Год издания: 2017
Издательство: Copernicus Gesellschaften
Местоположение издательства: Germany
Первая страница: 11
Последняя страница: 23
DOI: 10.5194/angeo-35-11-2017
Аннотация: We investigate the response of quasi-adiabatic particles to short-lived reconfigurations of the magnetotail field lines. Although they travel through a sharp field reversal with characteristic length scale smaller than their Larmor radii, these quasi-adiabatic (Speiser-type) particles experience negligible net changes of magnetic moment. We examine the robustness of these quasi-adiabatic particles in the presence of a large surging electric field induced by a magnetic field line reconfiguration. We demonstrate that, although this short-lived electric field can lead to significant nonadiabatic heating, quasi-adiabaticity may be, at least partially, conserved for particles with initial velocities larger than the peak ExB drift speed. Because of the time-varying character of the magnetic field, it is not possible to make use of the traditional adiabaticity parameter ? to characterize the particle behavior. Still, we demonstrate that particles that intercept the field reversal in the early stage of the reconfiguration may experience prominent energization (several keVs) and enhanced oscillating motion in the direction normal to the midplane. On the other hand, particles interacting with the field reversal in the late stage of the reconfiguration exhibit weaker energization and slower oscillations about the midplane. We show that, as a result of the surging electric field, quasi-adiabatic particles that originate from regions of strong magnetic field can travel down to low altitudes where they lead to characteristic energy-time dispersion signatures as observed in the plasma sheet boundary layer.
Добавил в систему: Малова Хельми Витальевна

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On the response of quasi-adiabatic ions to magnetotail reconfigurationsстатья

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