Electron-acoustic solitary waves in the presence of a suprathermal electron component

TL;DR

This paper investigates the nonlinear behavior of electron-acoustic solitary waves in a plasma with suprathermal hot electrons, revealing how their properties depend on the electron distribution's spectral index and plasma parameters.

Contribution

It introduces a model for electron-acoustic waves with suprathermal hot electrons using a kappa distribution and analyzes solitary wave characteristics with a pseudopotential approach.

Findings

Negative polarity solitary waves exist only within specific parameter regions.

Increasing suprathermality narrows the existence domain of solitary waves.

Soliton amplitude varies with spectral index and Mach number.

Abstract

The nonlinear dynamics of electron-acoustic localized structures in a collisionless and unmagnetized plasma consisting of "cool" inertial electrons, "hot" electrons having a kappa distribution, and stationary ions is studied. The inertialess hot electron distribution thus has a long-tailed suprathermal (non-Maxwellian) form. A dispersion relation is derived for linear electron-acoustic waves. They show a strong dependence of the charge screening mechanism on excess suprathermality (through \kappa). A nonlinear pseudopotential technique is employed to investigate the occurrence of stationary-profile solitary waves, focusing on how their characteristics depend on the spectral index \kappa, and the hot-to-cool electron temperature and density ratios. Only negative polarity solitary waves are found to exist, in a parameter region which becomes narrower as deviation from the Maxwellian (suprathermality) increases, while the soliton amplitude at fixed soliton speed increases. However, for a constant value of the true Mach number, the amplitude decreases for decreasing \kappa.