Plasmasphere Response: Tutorial and Review of Recent Imaging Results J. Goldstein (jgoldstein@swri.edu) Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio TX 78238 USA The plasmasphere is the cold, dense innermost region of the magnetosphere that is populated by upflow of ionospheric plasma along geomagnetic field lines. Driven directly by dayside magnetopause reconnection, enhanced sunward convection erodes the outer layers of the plasmasphere. Erosion causes the plasmasphere outer boundary, the plasmapause, to move inward on the nightside and outward on the dayside to form plumes of dense plasma extending sunward into the outer magnetosphere. Coupling between the inner magnetosphere and ionosphere can significantly modify the convection field, either enhancing sunward flows near dusk or shielding them on the night side. The plasmaspheric configuration plays a crucial role in the inner magnetosphere; wave-particle interactions inside the plasmasphere can cause scattering and loss of warmer space plasmas such as the ring current and radiation belts. _______________ Submitted, 2005 ISSI Workshop Proceedings, Space Science Reviews, 2005