Filamentation of Langmuir waves and the role of absolute decay instability in the electron foreshock: comparison of CLUSTER observations and theory

Details Filamentation of Langmuir waves and the role of absolute decay instability in the electron foreshock: comparison of CLUSTER observations and theory Filamentation of Langmuir waves and the role of absolute decay instability in the electron foreshock: comparison of CLUSTER observations and theory

Dec 2003

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003agufmsm32d..07s&link_type=abstract

American Geophysical Union, Fall Meeting 2003, abstract #SM32D-07

Computer Science

Sound

2772 Plasma Waves And Instabilities, 2784 Solar Wind/Magnetosphere Interactions

Scientific paper

Statistical analysis of HF electric field observed by WBD instrument on CLUSTER in the electron foreshock region show that the distribution of wave amplitudes depends on the scale of their modulation. In many cases the HF spectrum has two distinct narrow peaks near the plasma frequency. In some of those cases, when the difference of frequencies can be resolved by the instrument and is above the lower limit of frequency response, a wave with frequency corresponding to this difference is also observed. These observations indicate the presence of decay instability. The energy distribution has log-normal form for small amplitudes and manifests strong deviations from gaussian form for amplitudes larger than 1 mV/m. This suggests that the properties of small and large amplitude waves are determined by different physical processes. Conventional theory of parametric instabilities in a homogeneous medium gives results independent on scale, that disagrees with these experimental results. We propose a theoretical model based on the hypothesis that the wave activity for relatively intense electric fields is concentrated in filaments directed along the magnetic field lines. In this case the absolute parametric instability can develop. This results in the formation of profiles of the electric field of secondary Langmuir wave and density perturbations associated with ion-sound waves that correspond to eigenmodes generated by this instability. The threshold is shown to be inversely proportional to the characteristic modulation scale. This is due to the effect of the leakage of the energy of secondary waves through the filament boundaries. Taking into account this additional damping we evaluated the dependencies of wave amplitudes on characteristic scale of the modulation in a stationary state. The analytical results are shown to be in a good agreement with statistical analysis of intense Langmuir waves observed by WBD instrument in the electron foreshock region.

Affiliated with

Also associated with

No associations

Rating

Filamentation of Langmuir waves and the role of absolute decay instability in the electron foreshock: comparison of CLUSTER observations and theory does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Filamentation of Langmuir waves and the role of absolute decay instability in the electron foreshock: comparison of CLUSTER observations and theory, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Filamentation of Langmuir waves and the role of absolute decay instability in the electron foreshock: comparison of CLUSTER observations and theory will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1649655