High frequency ion sound waves associated with Langmuir waves in type III radio burst source regions - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Nonlinear Processes in Geophysics Année : 2004

High frequency ion sound waves associated with Langmuir waves in type III radio burst source regions

Résumé

Short wavelength ion sound waves (2-4kHz) are detected in association with the Langmuir waves (~15-30kHz) in the source regions of several local type III radio bursts. They are most probably not due to any resonant wave-wave interactions such as the electrostatic decay instability because their wavelengths are much shorter than those of Langmuir waves. The Langmuir waves occur as coherent field structures with peak intensities exceeding the Langmuir collapse thresholds. Their scale sizes are of the order of the wavelength of an ion sound wave. These Langmuir wave field characteristics indicate that the observed short wavelength ion sound waves are most probably generated during the thermalization of the burnt-out cavitons left behind by the Langmuir collapse. Moreover, the peak intensities of the observed short wavelength ion sound waves are comparable to the expected intensities of those ion sound waves radiated by the burnt-out cavitons. However, the speeds of the electron beams derived from the frequency drift of type III radio bursts are too slow to satisfy the needed adiabatic ion approximation. Therefore, some non-linear process such as the induced scattering on thermal ions most probably pumps the beam excited Langmuir waves towards the lower wavenumbers, where the adiabatic ion approximation is justified.
Fichier principal
Vignette du fichier
npg-11-411-2004.pdf (236.03 Ko) Télécharger le fichier
Origine : Accord explicite pour ce dépôt
Loading...

Dates et versions

hal-00302358 , version 1 (18-06-2008)

Identifiants

  • HAL Id : hal-00302358 , version 1

Citer

G. Thejappa, R. J. Macdowall. High frequency ion sound waves associated with Langmuir waves in type III radio burst source regions. Nonlinear Processes in Geophysics, 2004, 11 (3), pp.411-420. ⟨hal-00302358⟩

Collections

INSU EGU
67 Consultations
171 Téléchargements

Partager

Gmail Facebook X LinkedIn More