Potential for electron acoustic mode in the coma of a weakly outgassing comet

Abstract

This study aims to explore the electron acoustic (EA) mode in the vicinity of comet 67P/Churyumov–Gerasimenko, considering the existence of multiple electron species. In Region I, where all three suprathermal, warm and cold electron populations present and in Region II, where only warm and cold electrons present there is a chance to observe the EA mode for the plasma parameters measured at the comet. At smaller wave number (k), hotter electrons whereas at larger k, the cold electrons cause damping of the mode, and the mode only propagates at intermediate wave lengths. In these regions, it is determined that the mode observation enhances with the streaming speeds of hotter species, and it could be observed even for , which is not possible at lower or in the absence of drift speeds. In Region III, both warm and suprathermal electrons significantly damp the mode and hence, it is non-observable for the reported plasma parameters, and the mode could be only observable for the temperature ratio and surprisingly, the most favorable density for the observation is . Here, and stand for suprathermal and warm electron temperatures, respectively.