Abstract:
We perform fluid simulations to examine the effect of ion thermal velocity on the formation and dynamics of solitary waves in an
unmagnetized two-component plasma consisting of ions and electrons. Based on the linear and nonlinear fluid theories, some of the previous
studies have reported that the plasma with the electron temperature greater than the ion temperature (i.e., Te > Ti) supports ion acoustic solitary
waves (IASWs), whereas the plasma with Te Ti supports electron acoustic waves (EASWs). In this paper, we have considered a wide
range of ion temperatures (with fixed electron temperature) to examine the criteria of temperature and thermal velocities in the generation
of EASWs and IASWs in plasmas. Our simulation shows that the plasma with Ti > Te possesses two wave modes depending on the ratio of
its thermal velocities. When the ratio of electron to ion thermal velocities R ¼ Vthe/Vthi > 1, the system supports the generation of IASWs,
whereas for R < 1, it supports the generation of EASWs. The analysis of characteristics like the amplitude, width, and phase speed of these
solitary waves implies that the EASWs have a negative potential, whereas the IASWs have the positive potential. The transition from IASWs
to EASWs occurs when the phase speed of the solitary wave exceeds the limiting value of
ffiffiffi3
p
Vthe. This simulation study presents the detailed
investigation of the evolution of EASWs and IASWs generated in plasmas having Ti > Te, which will have implications in modeling such
waves in space and laboratory plasmas.
