Zakharov simulations of beam‐induced turbulence in the auroral ionosphere

• Published in: Journal of geophysical research. Space physics 2016-05, Vol.121 (5), p.4811-4825
• Main Authors: Akbari, H., Guio, P., Hirsch, M. A., Semeter, J. L.
• Format: Article
• Language: English
• Subjects: Auroral electrons; Auroral ionosphere; Auroral zones; beam‐plasma interaction; Coalescence; Decay; Density; Dynamics; Electron beams; F region; Fluid flow; Incoherent scatter radar; Ionosphere; Ionospheric electrons; ISR; Landau damping; Langmuir turbulence; Langmuir waves; Radar; Radar echoes; Simulation; Turbulence; Turbulent flow; Wave interaction
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1002/2016JA022605

Recent detections of strong incoherent scatter radar echoes from the auroral F region, which have been explained as the signature of naturally produced Langmuir turbulence, have motivated us to revisit the topic of beam‐generated Langmuir turbulence via simulation. Results from one‐dimensional Zakharov simulations are used to study the interaction of ionospheric electron beams with the background plasma at the F region peak. A broad range of beam parameters extending by more than 2 orders of magnitude in average energy and electron number density is considered. A range of wave interaction processes, from a single parametric decay, to a cascade of parametric decays, to formation of stationary density cavities in the condensate region, and to direct collapse at the initial stages of turbulence, is observed as we increase the input energy to the system. The effect of suprathermal electrons, produced by collisional interactions of auroral electrons with the neutral atmosphere, on the dynamics of Langmuir turbulence is also investigated. It is seen that the enhanced Landau damping introduced by the suprathermal electrons significantly weakens the turbulence and truncates the cascade of parametric decays. Key Points Dynamics of Langmuir turbulence as would be produced by auroral electron beams at the F region peak are investigated Suprathermal electrons, as modeled by Kappa distribution, have a significant effect on the development of Langmuir turbulence Wave products of three wave coalescence‐like interactions may be intense enough to be detected by incoherent scatter radars