Ion finite motion in disturbed magnetosphere with nonequipotential magnetic field lines.
Abstract
A three-dimensional ring current particle motion in the magnetosphere is simulated numerically. Both the dipole and Tsyganenko models. The convection electric field is described by the Volland-Stern model in equatorial plane an assumption to be the same out of the equatorial plane. It implies nonequipotentiality of the geomagnetic field lines that is possible for L>6 in disturbed magnetosphere conditions. The protons of several tens of keV starting from the night side of L=4 and drifting within the equatorial plane mostly under gradient magnetospheric drift abruptly depart from the equatorial plane at some point in their ExB transport trajectory and move towards high latitude regions. This latter motion is essentially confined to a plane perpendicular to the equator and is characterized by finite periodic latitudinal motion. The calculations further indicated sudden violation of the first adiabatic invariant at the point of departure from the equatorial region, with slow variation latter along the orbit. The greater the convection electric field the higher is the energy of the protons participating in this off equatorial flow. These result indicate that this perpendicular flow can significantly contribute to the morning-evening component of the magnetic field perturbation at storm time, populating the high latitude region by protons with energy around tens of keV.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....6761G