Stability and evolution of electromagnetic solitons in relativistic degenerate laser plasmas

Abstract

The dynamical behaviours of electromagnetic (EM) solitons formed due to nonlinear interaction of linearly polarized intense laser light and relativistic degenerate plasmas are studied. In the slow-motion approximation of relativistic dynamics, the evolution of weakly nonlinear EM envelope is described by the generalized nonlinear Schrödinger (GNLS) equation with local and nonlocal nonlinearities. Using the Vakhitov–Kolokolov criterion, the stability of an EM soliton solution of the GNLS equation is studied. Different stable and unstable regions are demonstrated with the effects of soliton velocity, soliton eigenfrequency, as well as the degeneracy parameter $R=p_{Fe}/m_ec$ , where $p_{Fe}$ is the Fermi momentum and $m_e$ the electron mass and $c$ is the speed of light in vacuum. It is found that the stability region shifts to an unstable one and is significantly reduced as one enters from the regimes of weakly relativistic $(R\ll 1)$ to ultrarelativistic $(R\gg 1)$ degeneracy of electrons. The analytically predicted results are in good agreement with the simulation results of the GNLS equation. It is shown that the standing EM soliton solutions are stable. However, the moving solitons can be stable or unstable depending on the values of soliton velocity, the eigenfrequency or the degeneracy parameter. The latter with strong degeneracy $(R>1)$ can eventually lead to soliton collapse.

Editorial: Wakefield generation and particle acceleration in high-intensity laser plasma and beam-plasma interactions

“…They have potential applications in laser fusion and particle accelerations. [7] studied the evolution of EM solitons in the non-linear interaction of circularly polarized intense EM waves with low-frequency electron-acoustic perturbations that are driven by the EM wave ponderomotive force in relativistic degenerate dense plasmas. They also studied the existence domains of EM solitons and their stability in the parameter space of soliton velocity and eigenfrequency.…”

Electromagnetic solitons and their stability in relativistic degenerate dense plasmas with two electron species

“…It is found that, an increase of each of R 0 , v 0 and k shifts the instability threshold λ s towards its higher values, implying that the stability domains (λ < λ s ) are significantly enhanced. This means that, in contrast to linearly polarized EM waves (Roy and Misra, 2020), the circularly polarized EM solitons cab be stable in high density degenerate plasmas with two-temperature electrons.…”

“…Furthermore, the existence of single-and multiple-peak solitary structures and their stability, mutual interaction and propagation in inhomogeneous cold plasmas were examined by Saxena et al (Saxena et al, 2006). Recently, using the Vakhitov-Kolokolov criterion, the stability and dynamical evolution of linearly polarized EM solitons were studied in the framework of a generalized nonlinear Schrödinger (GNLS) equation in relativistic degenerate dense plasmas (Roy and Misra, 2020). However, the present work considers the interactions of circularly polarized EM waves with two groups of electrons (one classical relativistic hot electron species with a small concentration and the bulk relativistic degenerate electron gas).…”

“…However, the present work considers the interactions of circularly polarized EM waves with two groups of electrons (one classical relativistic hot electron species with a small concentration and the bulk relativistic degenerate electron gas). While the two-electron species in plasmas support low-frequency electron-acoustic waves Misra et al (2021), the single species electrons with stationary background of ions as in (Roy and Misra, 2020) are rather relevant for high-frequency Langmuir waves. So, the evolution equations and the results, to be obtained in the present study, will be significantly different from those of the work of (Roy and Misra, 2020).…”

“…While the two-electron species in plasmas support low-frequency electron-acoustic waves Misra et al (2021), the single species electrons with stationary background of ions as in (Roy and Misra, 2020) are rather relevant for high-frequency Langmuir waves. So, the evolution equations and the results, to be obtained in the present study, will be significantly different from those of the work of (Roy and Misra, 2020). In an another work, the nonlinear coupling of EM waves and low-frequency electron-acoustic density fluctuations was considered by Shatashvili et al (Shatashvili et al, 2020) in relativistic astrophysical plasmas with two-temperature electrons.…”