Double Layers and Solitary Structures Observed in Ion Acoustic Mode Around Critical Regime and Its Possible Precursory Mechanism

By employing both perturbative and nonperturbative techniques, we study the small and large amplitude stationary formations of ion acoustic waves in plasma containing relativistically degenerate electrons. We derive the expressions for double layers and solitons following Sagdeev’s pseudopotential approach. Such a stationary structure becomes interesting around the critical density. To study the nonlinear formations around the critical region, we obtained the modified Korteweg–de Vries (m-KdV) equation and analyzed its parametric dependence. We have obtained kink and Gardner solitons and studied the parametric dependence. In addition, we have studied the wave–wave interaction, and the subsequent phase shifts have been studied with reference to various parameters. These are a precursor to the attainment of criticality in the problem. These findings will help in laser–plasma interactions regarding the relaxation time and the energy context. Short-pulse lasers and their applicability in various plasma applications may be predicted from these findings.