Observations of Plasma Injection

Abstract

Study of local plasma injection events observed at synchronous altitudes indicates that the plasma energy distribution function can be characterized as Maxwellian with one or more temperature components. Pitch angle features demand that more than one energization mechanism and perhaps more than one plasma source must be involved. The distribution function goes through drastic changes only during the first few minutes of the injection (peaks in the proton distribution function observed initially disappear within approximately one minute). Electron beams peaked at keV energies often accompany onset of the injection. These beams are characteristic of ionospheric potentials and no doubt play important roles in injection dynamics. The hotter component (E ≳ 10 keV) are probably of plasma sheet origin.