Modelling the plasma dynamics of the CRRES G-9 and G-10 barium releases

The CRRES mission involved a number of chemical releases in the ionosphere and magnetosphere to study a multitude of scientific phenomena. In this paper two releases are discussed: the G-9 release and the G-10 release. One of the primary purposes of the G-9 release was to study the transverse motion (i.e., `skidding') of plasma across magnetic field lines. Analysis of optical images indicates that the barium cloud `skidded' ~ 9 - 15 km. The simulation study is based upon a 2D electrostatic code which incorporates a time-dependent model of coupling to the background ionosphere. The simulation results indicate the densest portion of the barium cloud `skids' ~ 15 km within the first 3 sec following the release, consistent with observations. The G-10 release was designed to study, in part, the formation and evolution of a diamagnetic cavity, as well as the stability of the barium plasma. The simulation results are obtained from a 2D Hall MHD code and show that (1) the plasma and field structure at time t <= 22 sec, and develop scale sizes ~ 10 - 15 km, and (2) the structuring of the plasma allows `blobs' of plasma to drift across the magnetic field. These results are consistent with optical and in situ magnetometer measurements.