Study of the relationship between diffuse auroral and plasma-sheet electron distributions

This thesis deals with the relationship between the diffuse auroral and plasma sheet electron distributions in the midnight region (+/- 2 hrs MLT) of the earth's magnetosphere. Past studies have suggested that electron cyclotron harmonic (ECH) waves in resonance are responsible for the pitch-angle diffusion of low-energy plasma-sheet electrons into the atmospheric loss cone and the resulting precipitation into the diffuse auroral ionosphere. However, the adequacy of ECH waves as the principal diffusion mechanism is currently in controversy and is tested empirically in this study. The data base used consisted of low-energy (50 eV to 25 keV) differential electron-flux measurements from the low altitude polar-orbit in P78-1 satellite and the near-geosynchronous SCATHA satellite taken when the two spinning satellites were in conjunction, i.e., located at points along the same geomagnetic field line. The P78-1 measurements provided electron pitch-angle distribution information within the loss cone during the conjunction events