| Significant increases in electron fluxes and energy densities in the ring current energy range (1-200 keV) have been observed during magnetic storms to L values as low as 2. In this dissertation we first investigate the processes responsible for these storm-time flux increases of ring current electrons, and quantify the contribution of electrons to the ring-current energy content. To examine the formation of the electron ring current, we simulate the guiding-center drift and loss of electrons from the plasma sheet to the inner magnetosphere during one hypothetical storm and two storm events with the Dungey magnetic field and Volland-Stern type of electric field models. The simulation results of the hypothetical storm are compared with Explorer 45 data.; With a ring current model that includes both ions and electrons, we study the effects of the ring current induced magnetic field on the dynamics and energization of the ring current itself. For this study, we have developed a magnetically self-consistent ring current model in 2D, in which there is force balance between the magnetic field and plasma. The magnetic field produced by drifting particles is updated periodically with a force-balance equation solver providing a force-balanced magnetic field. The hypothetical storm is simulated with this magnetically self-consistent ring current model. The simulated magnetic fields show that the magnitude of the disturbed magnetic field intensity can be -200 nT at geocentric radial distance of 3 RE in the equatorial plane. This magnitude of magnetic field intensity agrees well with statistical studies based on observational data in terms of spatial distribution and magnitude. Comparisons of simulation results from the self-consistent and non-self-consistent models reveal that the distorted magnetic configuration and the induced electric field magnetic field tend to prevent ring current particles from deeper injection, and to mitigate the energization during the injection. These results show the need for not only testing ring current models with in situ particle data, but also with in situ magnetic field data. (Abstract shortened by UMI.)... |
