Trans-geosynchronous Characteristics of Plasma and Energetic Particles Using SCATHA Data

The SCATHA satellite made several years of detailed plasma, energetic particle and magnetic field observations over geocentric radial distances of 5.5 to 7.5. Thus SCATHA provides the capability to characterize the particle environment both external and internal to geosynchronous orbit. This allows one to infer relationships between parameters such as the characteristic energy of electrons and ions and the hot plasma density as functions of radial distances, that span geosynchronous, local time and magnetic conditions. One minute summary SCATHA plasma and energetic particle data were used to calculate the average energies for the electrons and protons and the hot plasma density and perpendicular pressure. For example, over a selected interval in the night side magnetosphere (post dusk to pre dawn) the average energy of the hot plasma protons (150 eV to 133 keV) decreases with increasing L (5.5<L<7) such that it is nearly twice as high at L=5.5 (23 keV) as it is at L=7 (12 keV), consistent with expected cross field energy gain from convection. At the same time the average (and mean) electron energy increased slightly with increasing L from 1.9 keV at L=5.5 to 2.2 keV at L=7. However the relative scatter in the electron average energy values was quite large. SCATHA also provides the phase space density (PSD) of energetic electrons over a wide range of first and second invariants. This allows one to assess the gradients in PSD with radial distance both near and off the magnetic equator. For example, during one moderate storm in April 1986 the PSD was observed to be monatomic near the magnetic equator while it show a peak near L*=5.5 Re well off the equator. These and other results will be shown and discussed in the context of what they show about the character of the energetic plasmas in radial regions that traverse geosynchronous orbit.