Electromagnetic Ion Cyclotron Waves, Plasma Plumes and Cold Ion Density Measurements 
in the Magnetosphere

B. J. Fraser, H. J. Singer, J. Goldstein, D. L. Gallagher, and M. Thomsen 


The radial plasma density profile in the plasmasphere-plasmapause region may vary
considerably depending on the particle species measured and the particular satellite
instrument making the measurement. For example the heavy ion relative concentrations
of He+and O+ compared with H+ ions, are not constant with increasing radial 
distance. Also, some satellites measure electron density, directly or indirectly, while
others measure H+ and He+. IMAGE-EUV satellite results have confirmed the existence
of plasma plumes in the middle magnetosphere and often electromagnetic ion cyclotron 
waves are observed within these plumes. This paper will introduce the relationship
between plumes and EMIC waves. It will then consider intercalibration between 
instruments measuring plasma density in the plasmasphere/magnetosphere and develop 
diagnostic techniques to compute heavy ion densities in plasma plumes. Using the 
spectral properties of EMIC waves seen in plumes in conjunction with ion density 
data and diagnostic techniques it is possible to almost completely describe the
plasmasphere and magnetosphere cold/cool plasma composition. Particle data from
the LANL geostationary satellites, EUV images from the IMAGE satellite and EMIC
wave data from the GOES satellites are used in this study. Results yield ion densities
ranging from over H+ = 30 � 80 cm�|3 and He+ = 7 � 13 cm^-3 and O+ = 5 � 9 cm^-3.
The He+ results are compared with computed pseudo-densities of He+ determined
from IMAGE-EUV data.

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European Geosciences Union General Assembly, Vienna, Austria, 2-7 April 2006