Caviton dynamics in strong Langmuir turbulence
Abstract
Recent studies based on long time computer simulations of Langmuir turbulence as described by Zakharov's model will be reviewed. These show that for strong to moderate ion sound samping the turbulent energy is dominantly in nonlinear caviton excitations which are localized in space and time. A local caviton model will be presented which accounts for the nucleation collapse burnout cycles of individual cavitons as well as their space-time correlations. This model is in detailed agreement with many features of the electron density fluctuation spectra in the ionosphere modified by powerful HF waves as measured by incoherent scatter radar. Recently such observations have verified a prediction of the theory that free Langmuir waves are emitted in the caviton collapse process. These observations and theoretical considerations also strongly imply that cavitons in the heated ionosphere, under certain conditions, evolve to states in which they are ordered in space and time. The sensitivity of the high frequency Langmuir field dynamics to the low frequency ion density fluctuations and the related caviton nucleation process will be discussed.
- Publication:
-
Presented at the International Centre for Theoretical Physics Conference
- Pub Date:
- 1989
- Bibcode:
- 1989ictp.conf...22D
- Keywords:
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- Cavitation Flow;
- Cavitons;
- Computerized Simulation;
- Dynamic Characteristics;
- Electric Fields;
- Turbulence;
- Earth Ionosphere;
- Energy Spectra;
- Landau Damping;
- Plasma Waves;
- Sound Waves;
- Space-Time Functions;
- Plasma Physics