Flux Tube Dynamics Following Pellet Release Experi- ments in Laboratory Magnetospheres

The rapid release of particles in the magnetosphere has allowed study of a wide range of space plasma dynamics including particle transport, magnetic bubble formation, and rapid flux-tube dynamics.\footnote{Bernhardt, \textit{Phys. Fluids B} \textbf{4}, 2249 (1992).} We report new experiments using the Levitated Dipole Experiment (LDX) (http://www.psfc.mit.edu/ldx/) where we explore the high-speed plasma dynamics following the release of 0.2~mm polystyrene pellets. The pellets are released into high-beta steady-state plasmas containing significant population of quasi-relativistic electrons. Similiar experiments, conducted in a smaller, mechanically-supported, laboratory magnetosphere show pellet ``explosions,'' electron precipitation, ``blob'' formation, and rapid changes of plasma density. A variety of diagnostics are available, including microwave reflectometry, high-speed videography, multi-tip probe arrays, and accurate magnetic reconstruction. Results and analyses will be reported along with plans for futher efforts to increase plasma density and conduct a variety of controlled physics experiments associated with magnetospheric events.