Density fluctuation effects on Langmuir wave propagation
Abstract
Linear mode conversion (LMC) occurs when Langmuir waves propagate in an inhomogeneous medium, so it is important to understand the effects on LMC of the density turbulence typically found in heliospheric plasmas. Although space plasmas typically contain density turbulence with large ranges of length scale L and orientations in 3D, most theoretical and numerical studies have focused on 1D linear density profiles. Other profiles are likely to yield semi-quantitative differences, as found previously for instance by comparing LMC for linear versus parabolic profiles. In this study, we examine the effects of superposing density fluctuations with a range of L onto linear density gradients. Langmuir waves are often observed as wave packets and this can result from short scale, weak, density fluctuations. Such small scale density fluctuations affect the wave propagation characteristics and wavevectors. Moreover, combining a linear density profile with superposed density fluctuations yielded trapped modes and resonant variations in the conversion efficiency. In particular, increased efficiencies are found when integer numbers of Langmuir wavelengths fit within one or more cavities formed by the superposed turbulence).
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2015
- Bibcode:
- 2015AGUFMNG41A1776K
- Keywords:
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- 3389 Tides and planetary waves;
- ATMOSPHERIC PROCESSES;
- 2483 Wave/particle interactions;
- IONOSPHERE;
- 4455 Nonlinear waves;
- shock waves;
- solitons;
- NONLINEAR GEOPHYSICS