Nonlinear Dynamics of Ion-Acoustic Waves in a Magnetized Plasma With Trapped Electrons

Abstract

The dynamics of obliquely propagating ion-acoustic waves (IAWs) in a collisionless, magnetized plasma consisting of free and trapped electrons, having a vortex-like distribution and fluid ions immersed in an external static magnetic field, has been investigated. The reductive perturbation technique (RPT) has been used to derive a Schamel’s modified Laedke–Spatschek (S–LS) equation. Several nonlinear structures have been obtained, like solitary waves, periodic and quasi-periodic oscillations, as well as chaotic structures. The effects of the magnetic field strength, the wave propagation obliqueness, the Mach number, and the electrons trapping on these nonlinear structures have been explored. The increase in the magnetic field strength has been found to reduce the soliton width and enhance its amplitude, while the role of rising the trapping parameter is only to increase the solitary wave amplitude. For a relatively weak magnetic field, the increase in the Mach number may change the solitonic structure to a periodic oscillation and the latter to a quasi-periodic one, while the decrease in the propagation angle to the magnetic field direction may bring about the second transition (periodic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\rightarrow$</tex-math> </inline-formula> quasi-periodic). Furthermore, depending on the plasma parameters, the intensification of the magnetic field can lead to the transition from a quasi-periodic to a chaotic behavior of the electrostatic wave.