Spatial localization of Langmuir waves generated by a suprathermal electron beam propagating in the solar wind

Large amplitude spatially localized Langmuir waves are frequently observed in the solar wind, usually correlated with the presence of suprathermal electron beams. Recent in-situ observations by the TDS instrument onboard the STEREO spacecrafts showed that this spatial localization could result from propagation effects of the Langmuir waves in the inhomogeneous solar wind plasma. We present a theoretical model and a numerical code based on the spectral resolution of the high frequency component of the Zakharov's equations in wich a term relative to beam particles has been introduced. We shall present and discuss simulation results of the destabilization of loacalized Langmuir waves by a an electron beam in the presence of density fluctuations.