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Fig. 4. ( Left ) Model electron trajectories during dipolarization. These trajectories are
shown ( top )inthe X - Z plane and ( bottom )inthe X - Y plane, the different colors
corresponding to different initial positions along the field line. Black lines in the upper
left panel show the magnetic field line before and after dipolarization. ( Right; from top to
bottom ) Grey-coded flux (normalized to the maximum value) and adiabaticity parameter
κ of electrons as a function of post-dipolarization time and energy. These variations are
shown at 1.5 R M radial distance and for two different temperatures (30 eV and 1 keV) of
the initial Maxwellian distribution (adapted from Ref. 17).
dipolarization. Here, the test particles were initialized with 10 eV energy
and 90 pitch angle at different locations (separated by equidistant steps of
500 km) along the field line. The convection surge due to the large electric
field induced by dipolarization of the magnetic field line (e.g., Ref. 20) is
clearly noticeable in these panels that display a rapid inward injection of
the electrons. Also, because of the low-energy character of the particles
(up to a few hundreds of eV after dipolarization), no significant drift in the
Y -direction can be seen in the bottom left panel.
The upper right panels of Fig. 4 show the energy-time spectrograms
obtained for electrons with 30 pitch angle. Note here that the initial elec-
tron distribution is assumed to be Maxwellian with two distinct initial
temperatures (30 eV and 1 keV). In addition, the bottom right panel of
Fig. 4 displays the minimum adiabaticity parameter κ encountered during
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