Momentum transfer in the combined release and radiation effects satellite plasma injection experiments: The role of parallel electric fields

Optical observations of the combined release and radiation effects satellite (CRRES) plasma injection experiments have revealed signatures of the coupling processes between the injected and ambient plasmas. The elongation of the ion cloud along the geomagnetic field indicated the presence of parallel electric fields. A dense core of ions polarized and ExB drifted along the satellite trajectory for 6-10 s. In an effort to understand the momentum coupling between the two plasma populations, a three-dimensional hybrid code is used. The simulation, which neglected electron inertia, showed a very efficient transfer of momentum via Alfven waves and the skidding ion core was stopped within 2 s. To reconcile the difference between the observed and simulated skidding times, we propose that the cloud must have been decoupled from the ambient plasma via parallel electric fields. The parallel fields may be associated with inertial Alfven waves propagating in filamentary current layers at the edges of the ion cloud, or due to a variety of possible plasma instabilities. The results of this study can be applied to coupling processes in other geophysical and astrophysical systems such as cometary environments, Io's plasma torus, and the auroral regions of the ionosphere and magnetosphere. (C) 2000 American Institute of Physics. [S1070-664X(00)03209-2].