HR: 0800h
AN: SM41A-1162    [Abstracts]
TI: Calculation of Bounce-Averaged Velocities and Hydrogen Densities for a Non-dipole Magnetic Field
AU: * Vapirev, A
EM: avapirev@unh.edu
AF: University of New Hampshire, Dept. of Physics 9 Library Way, Durham, NH 03824 United States
AU: Jordanova, V
EM: vania.jordanova@unh.edu
AF: University of New Hampshire, Dept. of Physics 9 Library Way, Durham, NH 03824 United States
AB: Conditions on the sun, in the solar wind and Earth's space environment often can influence the performance and reliability of spacecrafts and ground-based systems. This is referred to as ``Space Weather''. Magnetic storms, a major part of space weather, develop when the coupling of the solar wind to the magnetosphere becomes strong and prolonged and the geomagnetic activity becomes intense. The ring current is an essential element of all geomagnetic storms. In previous work values valid for a dipole magnetic field approximation have been used to calculate the particle bounce period and the second adiabatic invariant, and to study the behavior of the trapped particles (Ejiri, 1978). In the present work we use a non-dipole magnetic field to numerically calculate the corresponding integrals for the bounce period and the second adiabatic invariant along the magnetic filed lines. We assume that all magnetic field lines are perpendicular to the equatorial plane at their intersection points in Solar Magnetic coordinate system. We use the same numerical technique to calculate the bounce-averaged Hydrogen densities and the bounce-averaged guiding center velocities. Then we calculate the relative difference for the above quantities and those for a dipole field for various values of the Kp-index. We find that for small Kp the difference is predominantly between -10% and +10% for the integrals calculated by Ejiri and it reaches values of around 50% for large Kp. The relative difference for the bounce-averaged Hydrogen densities is around 5% for small Kp, while for large Kp it is more than 15%. The corresponding results for the bounce-averaged velocities are respectively around 3% and more than 20%. The relative difference is larger towards the dusk-midnight side for all calculations.
DE: 2720 Energetic particles: trapped
DE: 2730 Magnetosphere: inner
DE: 2753 Numerical modeling
DE: 2778 Ring current
DE: 6939 Magnetospheric physics (2700)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005