Chaos in the dynamics of electromagnetic solitons in relativistic degenerate plasmas

TL;DR

This paper investigates the nonlinear dynamics of electromagnetic solitons in relativistic degenerate plasmas, revealing how degeneracy and nonlocal effects influence stability, modulational instability, and the emergence of chaotic states.

Contribution

It introduces a coupled nonlinear model including higher-order nonlocal effects and demonstrates the impact of degeneracy on soliton stability and chaos in relativistic plasmas.

Findings

Degeneracy reduces modulational instability growth rates.

Higher nonlocal correction narrows the instability domain.

Temporal chaos indicates potential spatiotemporal chaos in the plasma.

Abstract

We propose a coupled system for the nonlinear interaction between high-frequency, circularly polarized, intense electromagnetic (EM) waves and low-frequency electron-density perturbations, driven by the EM-wave ponderomotive force, in an unmagnetized plasma composed of fully degenerate relativistic electrons and stationary positive ions, including a higher-order correction to the nonlocal nonlinearity. We show that the modulational instability (MI) growth rate associated with the generation of EM envelope solitons gets significantly reduced with a slight increase in either the nonlocal nonlinear correction or the degeneracy parameter. Furthermore, a three-wave temporal model predicts the existence of quasiperiodic and chaotic states of EM solitons while interacting with longitudinal electron density perturbations. We show that the greater the degeneracy (or the higher the contribution from the nonlocal correction), the smaller the instability domain of modulation wave numbers; thus, degeneracy favors the stability of EM soliton evolution. The existence of temporal chaos in a low-dimensional model could be a signature of the development of spatiotemporal chaos in the complete nonlinear model, in which many electromagnetic solitons can be excited and saturated as they interact with electron plasma waves.