Abstract:
Electrostatic solitary waves (ESWs) and double layers are explored in a four-component plasma
consisting of hot protons, hot heavier ions (Heþþ), electron beam, and suprathermal electrons having
j-distribution using the Sagdeev pseudopotential method. Three modes exist: slow and fast
ion-acoustic modes and electron-acoustic mode. The occurrence of ESWs and their existence
domain as a function of various plasma parameters, such as the number densities of ions and electron
beam, the spectral index, j, the electron beam velocity, the temperatures of ions, and electron
beam, are analyzed. It is observed that both the slow and fast ion-acoustic modes support both positive
and negative potential solitons as well as their coexistence. Further, they support a “forbidden
gap,” the region in which the soliton ceases to propagate. In addition, slow ion-acoustic solitons
support the existence of both positive and negative potential double layers. The electron-acoustic
mode is only found to support negative potential solitons for parameters relevant to the lunar wake
plasma. Fast Fourier transform of a soliton electric field produces a broadband frequency spectrum.
It is suggested that all three soliton types taken together can provide a good explanation for the
observed electrostatic waves in the lunar wake.
