Non-linear coherent structures in multi-species dusty plasma

In a fluid description, theoretical investigation has been carried out to explore how the presence of two-temperature electron fluids (hot and cold) influences the characters of dust acoustic solitary waves, double layers, bipolar structures, etc. in a multi-component dusty plasma, composed of isothermal electrons and ions, along with the negatively charged, cold dusts. A reductive perturbation method is used to derive the well-known Korteweg-de Vries (KdV) equation, which describes the basic nature of the dust acoustic solitary waves. Two values of critical ion density exist, which distinguish the regions of compressive and rarefactive solitary waves in parametric space. The critical points directly depend on the densities and temperatures of the electron fluids. With increasing temperature of hot electron fluid, one of the two critical ion densities decreases, and the other one increases. Ultimately, they merge with each other when the temperature of hot electrons reaches a particular value. The amplitude of the dust acoustic soliton gets modified due to the presence of two-temperature electron fluids. The study is extended further by deriving modified KdV and Gardner equations at the vicinity of critical points. The Gardner equation reveals the existence of double layer and bipolar structures. In these processes, the effects higher-order nonlinearities are incorporated methodically, by implementing appropriate stretching of the coordinates. Sagdeev's pseudopotential analysis shows that large amplitude rarefactive solitary waves only exist when the corresponding Mach number (M) lies within 1 < M < M-c. The upper bound, M-c increases with the hot electron temperature and cold electron density. The results presented in this investigation are believed to be applicable in the laboratory and astrophysical plasmas.

Automated summary

In this theoretical investigation, the presence of two-temperature electron fluids (hot and cold) in a multi-component dusty plasma was studied to understand their impact on dust acoustic solitary waves, double layers, and bipolar structures. Critical ion density values were found to determine compressive and rarefactive solitary waves regions in parametric space, with the critical points dependent on the densities and temperatures of the electron fluids. The study also revealed modifications in the dust acoustic soliton amplitude with increasing temperature of the hot electron fluid and the existence of double layer and bipolar structures via the Gardner equation.