Empty Flux Tubes and Plasmasphere Refilling as Seen by IMAGE D. L. Gallagher, M. L. Adrian, and G. V. Khazanov, NASA/Marshall Space Flight Center, Huntsville, AL 35812 J. L. Green NASA/Goddard Space Flight Center, Greenbelt, MD 20771 P. Song, B. Reinisch Center for Atmospheric Research, University of Massachusetts, Lowell, MA 01854 B. R. Sandel Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 When a plasmaspheric flux tube is empty, what plasma is actually missing? When a flux tube refills, where does the plasma accumulate first? How long does it take to refill a flux tube to a level that is essentially saturated? Owing to the observational difficulties of measuring the distribution of plasmaspheric plasma along a flux tube, these questions have remained unanswered over many decades of study since discovery of the plasmasphere. They are important questions, because of the role that plasmaspheric plasma plays in collisional losses of higher energy populations, in modifying instabilities for wave-particle interactions, and in influencing the transport of energy through plasma waves. The Extreme Ultraviolet Imager and the Radio Plasma Imager on the IMAGE Mission are providing new, critical observations of the dynamic outer plasmasphere where convective erosion and refilling dominate. Latitudinal density profiles along a single L-shell from RPI confirm earlier indications of a mid-latitude transition between the altitude organized structure of the ionosphere and L-shell organized plasmasphere. Emptied flux tubes often mean empty only above about 1 Re in altitude or below +- 40 degrees in magnetic latitude. Refilling to nearly saturated levels is found to take much less than that previously found necessary to complete the process. The observations behind these conclusions, as well as their potential applications for plasmaspheric physics, will be discussed. Also to be discussed is the quantitative relationship between plasmasphere refilling theory and these new observations. _______________ To be presented at the 2002 Spring A.G.U. Meeting, Washington, D.C., U.S.A., 28-31 May 2002