Excitation of electrostatic fluctuations by jets in a flaring plasma

Abstract

Context. During magnetic reconnection as the proposed basic process of solar flares, hot high speed plasma streams (jets) are ejected from the reconnection site. Jets are sometimes associated with type III radio bursts as signatures of electron beams in the solar corona. Aims. The interaction of such a jet with the surrounding coronal plasma is investigated concerning the generation of electrostatic fluctuations. Methods. The conditions of excitations of such waves are studied in detail under coronal conditions by solving the linearized Vlasov-Maxwell equations. Results. The interaction of a jet with the background plasma leads to an instability for a small range of jet speeds exciting electrostatic waves in the sense of the ion-acoustic mode. Electrons can be energized by their interaction with these electrostatic fluctuations. Such energetic electrons can be the source of type III radio bursts and/or non-thermal X-ray radiation as observed during solar flares. © ESO 2007.