Abstract:
We examine the characteristics of fast electron-acoustic solitons in a four-component unmagnetised
plasma model consisting of cool, warm, and hot electrons, and cool ions. We retain the inertia and
pressure for all the plasma species by assuming adiabatic fluid behaviour for all the species. By using
the Sagdeev pseudo-potential technique, the allowable Mach number ranges for fast electronacoustic
solitary waves are explored and discussed. It is found that the cool and warm electron number
densities determine the polarity switch of the fast electron-acoustic solitons which are limited by
either the occurrence of fast electron-acoustic double layers or warm and hot electron number density
becoming unreal. For the first time in the study of solitons, we report on the coexistence of fast
electron-acoustic solitons, in addition to the regular fast electron-acoustic solitons and double layers
in our multi-species plasma model. Our results are applied to the generation of broadband electrostatic
noise in the dayside auroral region.
