Non-monotonic double layers and electron two-stream instabilities resulting from intermittent ion acoustic wave growth
Abstract
Transient characteristics of a current-carrying plasma subjected to ion acoustic instability are studied via Vlasov–Poisson simulations. After saturation of the ion acoustic instability, when a sufficient range of long-wavelength ion acoustic modes is considered, ion acoustic wave packets form and give rise to ion phase space holes. These ion holes grow in magnitude until asymmetric electron reflection, due to the current carrying plasma, results in a potential gradient across the hole known as a non-monotonic double layer. Downstream of the double layer, an electron two-stream instability is generated due to a depletion of forward-streaming electrons by reflection. This secondary instability initiates a plasma wave whose phase velocity is determined by the magnitude of the double layer potential. While the double layer potential depends on the ion mass for a given domain length, the phase velocity of the secondary wave is consistently observed to be greater than the ion acoustic speed. Implications for the presence of these transient phenomena are discussed in the context of experimental plume measurements of hollow cathode devices.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 01, 2020
- Source ID
- 10.1063/5.0019729
Entities
People
- Alexander R. Vazsonyi
- Iain D. Boyd
- Kentaro Hara
Organizations
- Air Force Office of Scientific Research
- Stanford University
- University of Colorado
- University of Michigan