Observations of Electron Cyclotron Harmonic Emissions Associated with Field-Aligned Electron Beams

摘要

Several cases have been found in plasma wave and electron distribution function data from the SCATHA satellite in which strong gyrofrequency emissions near 1.5 times the local electron gyrofrequency, f sub g, correlate in time with field-aligned electron beams. The energy of the electron beams ranges from 100 to 800 eV. Before the beam appears the emissions are observed at a lower frequency, typically 1.1 to 1.2 f sub g. As the beam develops, the emissions rise in frequency and grow in amplitude. Above 2 keV the electrons had a normal loss-cone distribution. This loss cone deepened by a small amount when the beams appeared at lower energy. These observations were made near local midnight between L=7.0 and 7.8 R sub e.