Outer Plasmasphere Irregularities and Plasmatails

Examples of OGO-5 and OGO-3 ion spectrometer measurements of light ion density irregularities in and/or beyond the outer plasmasphere at different local times are compared to the expected plasmasphere evolution based on a simple convection model. The model traces the motion of magnetic flux tubes as the equatorial convection E field varies in step with Kp. Structures similar to the observed "detached" regions are readily produced by the model. However these structures appear in the model as tail-like extensions of the plasmasphere (i.e., plasma structures which are topologically attached to the inner plasmasphere). Such plasmatails with their attendant motions and wrappings about the earth can produce fine structured density variations. Each plasmapause boundary is predicted to consist of an irregular region of multiple plasmatails. Periodic substorm recurrences with a period between storms of 1-2 days seem to result in the most complex broad scale features.