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Current‐driven Langmuir oscillations and formation of wave packets via modulational instability: Relevance to STEREO observations
Author(s) -
Sauer K.,
Sydora R. D.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl069872
Subject(s) - modulational instability , physics , langmuir turbulence , plasma oscillation , instability , solar wind , plasma , electron , electric field , population , atomic physics , computational physics , waves in plasmas , two stream instability , mechanics , demography , quantum mechanics , sociology
Recently, it has been shown that Langmuir oscillations (LOs) at the plasma frequency can be driven by an electron current without any electrostatic instability. This current may appear due to a (small) drift of the whole electron population against the ions or by beam electrons after their relaxation to a plateau‐like distribution. The consequences of LOs for nonlinear wave phenomena in this scenario are studied by means of kinetic plasma simulations. It is shown that the electric field of LOs can act as a pump wave and generate Langmuir envelope solitons via the modulational instability. In this way, both counterstreaming Langmuir and ion‐acoustic waves arise with the same wave number. For solar wind conditions the Doppler shift leads to the generation of satellite peaks with frequencies symmetric around the plasma frequency. Simultaneously, a peak appears in the ion‐acoustic branch. These results agree well with recent STEREO observations in the solar wind.