Magnetospheric Electron Densities and Electron Density Structures Determined 
from the RPI on IMAGE

Robert F. Benson
Laboratory for Extraterrestrial Physics
NASA/Goddard Space Flight Center


The Radio Plasma Imager (RPI) on the Imager for Magnetopause-to-Aurora Global 
Exploration (IMAGE) satellite stimulates local plasma resonances and long-range 
echoes.  The resonances can be used to accurately deduce both the in situ 
electron density Ne (to within ~ 1%) and the magnetic field strength (to within 
~ 0.1%) even in very tenuous plasmas where the former is difficult to measure.  
The long-range echoes can be used to derive Ne profiles between the satellite 
location and the reflection region (often many RE distant).  Both are possible 
only if a proper classification can be made of the observed signal returns.  
This presentation will illustrate how this classification is made and how the 
results have been applied to interpret both active and passive RPI records in 
different parts of the IMAGE orbit with particular emphasis on the plasmapause 
boundary region and near the 8 RE IMAGE apogee.  Observations from the latter 
region will include comparisons between before and during the large magnetic 
storm of 31 March 2001.

_______________
To be presented at the Laboratory for Extraterrestrial Physics Brownbag Seminar, 
12 April 2002, Noon, Conference Room (Room 8) in Building 2, GSFC.