Destabilization mechanisms of electrostatic solitary waves in ion-acoustic regimes within collisionless cometary plasma

This study investigates the dynamics of instability and energy of ion-acoustic waves (IAWs) in a magnetized, five-component cometary plasma comprising inertial hydrogen ions (H⁺), positively/negatively nonextensive charged oxygen ions (O^±), and superthermal-distributed solar/cometary electrons. The work results in deriving the Zakharov-Kuznetsov (ZK) equation under nonextensive ion effects, showing how wave stability and energy transmission are governed by electron superthermality, ion nonextensivity, and magnetic geometry. The findings show that phase velocity increases with solar electron densities and superthermality, but decreases with ion nonextensivity of oxygen ions, emphasizing the competition between the ion-driven dissipation and electron thermal pressure. Increased Landau damping and increased electron pressure cause lower negative oxygen ion density to amplify the instability growth rate, gr, by upsetting charge neutrality and causing ion drifts; higher electron densities, on the other hand, cause gr to increase. Energy, E_n, accumulates with solar electron density, oblique propagation, θ, and weaker magnetic fields, ω, via enhanced nonlinear steepening and dispersive broadening. In contrast, gr peaks at parallel propagation (θ→0°) but declines at oblique angles (θ>θ_c) as a result of magnetic stabilization. Notably, magnetic fields suppress gr at high θ while enhancing E_n through wave broadening. The study identifies a critical distinction: E_n depends on nonlinearity-dispersion balance, whereas gr hinges on electron–ion coupling and resonant interactions. By connecting microscopic wave activity to macroscopic instability thresholds, these findings provide cometary plasma models forward and help to understand Rosetta mission data and forecast wave-driven heating in cometary environments.