Dynamics of nonlinear ion-acoustic waves in Venus’ lower ionosphere

Abstract

Dynamics of nonlinear ion-acoustic waves (IAWs) are studied for Venus’ lower atmosphere at an altitude of \(200-1000\) km. Two-soliton, nonlinear solitary and periodic waves in a three-component plasma consisting of \(H^{+}\) and \(O^{+}\) ions with kappa distributed electrons are studied. Using the reductive perturbation technique (RPT), the Korteweg-de Vries (KdV) equation is derived and a Planar dynamical system is formed for the KdV equation using a travelling wave transformation. A phase portrait is drawn to analyze nonlinear wave behaviors by adjusting the parameters \(\kappa \) (spectral index), \(\gamma \) (unperturbed number density ratio), and \(V\) (travelling wave speed). Increasing values of \(\kappa \) amplify amplitudes for solitary and periodic waves, narrow down the width of the solitary wave, and broaden the width of the periodic wave. Increasing value of \(\gamma \) boosts amplitude of the solitary wave with unchanged width, while amplitude of the nonlinear periodic wave decreases and width widens. Increasing value of \(V\) enhances amplitudes and reduces widths for both solitary and periodic waves. Two-soliton solutions for the KdV equation are studied using the Hirota direct method. Increasing value of \(\gamma \) reduces amplitude of the soliton without affecting the width and increasing value of \(\kappa \) reduces width of the soliton. Phase shift for two-soliton is also shown and found that for different values of \(\kappa \), the phase shift increases on increasing value of \(\gamma \). The findings of our result aid in understanding the dynamics of nonlinear waves and two-soliton solutions in Venus’ lower ionosphere.