Beam-Plasma Interactions and Radiation Generation during the Ejection of Electron and Ion Beams in Space
Abstract
Multi-dimensional electrostatic and electromagnetic particle simulations are used to investigate the nature of beam-plasma interactions and radiation generation during the injection of dense electron beams into the ionosphere from spacecraft. The nature of the injection process is determined primarily by the relative value of two characteristic time scales: the beam stagnation time t (s) and the plasma response time t(rp). When ts < trp, spacecraft charging is significant and most of the beam electrons are drawn back into the spacecraft. When ts>trp, vehicle charging is reduced and the beam propagates away from the source. In this latter case there is strong beam-plasma turbulence which destroys the coherence of the beam within one or two gyroperiods. The spatial distribution of the beam has the form of a hollow cylinder near the source. As the beam propagates away from the source, the cylinder becomes increasingly filled. Return currents are associated with the field-aligned flow of ambient electrons, while current closure is provided primarily by the cross-field motion of the ions. The beam-plasma interaction leads to the formation of coherent current structures. Whistler waves with a peak in the frequency range 0.5 - 0.7 omega e are produced by these structures via a coherent Cerenkov interaction. The Whistler waves propagate at angles substantially away from the resonance cone are are predominantly electromagnetic in nature.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1992
- Accession Number
- ADA253993
Entities
People
- D. Schriver
- H. Okuda
- M. Ashour-abdalla
- P. L. Pritchett
Organizations
- University of California, Los Angeles