Electron Cyclotron Harmonic Waves Observed by the AMPTE-IRM (Active Magnetospheric Particle Tracer Explorers-Ion Release Module) Plasma Wave Experiment Following a Lithium Release in the Solar Wind

摘要

An unexpected occurrence following the second lithium release by the AMTPE-IRM spacecraft in the solar wind was the appearance of electrostatic electron harmonic (ECH) emissions. These emissions began about 50 sec after the release and continued for several minutes. Narrow band emissions polarized perpendicular to the magnetic field were present in each of the first five harmonic bands. Unpolarized broadhand emissions were also present at the same time. The broadhand emissions extended from below the electron cyclotron frequency to above the highest ECH band. Both emissions were entirely electrostatic because no accompanying signals were detected by the magnetic antenna. Candidate generation processes include the ion acoustic and the electron cyclotron drift instabilities. These instabilites would be driven by the relative drift of the lithium ions and the solar wind electrons. It will be shown that the calculated growth rates of these processes are sufficient to account for the measured waves, but that the observed lack of a Doppler shift of the ECH bands is inconsistent with the theory. Keywords: Plasma Waves; Chemical Release.