Nonlinear plasma waves in an electron gas

TL;DR

This paper investigates nonlinear plasma wave solutions in a three-dimensional electron gas, revealing distinct soliton and wave behaviors depending on whether the plasma motion is subsonic or supersonic.

Contribution

It characterizes the existence and properties of solitons and periodic waves in an electron gas, highlighting differences between subsonic and supersonic regimes.

Findings

Solitons exist in the subsonic regime as localized depressions.

Two types of periodic waves are found in the supersonic regime.

Distinct wave structures depend on the flow speed relative to sound.

Abstract

The nature of traveling wave solutions to equations of hydrodynamics of a generic three-dimensional electron gas with parabolic dispersion law depends on whether the motion is subsonic or supersonic. Solitons representing localized depressions of the electrostatic potential and electron density are predicted to exist in the subsonic regime: at rest the solitons are dark while in motion they are grey. Two types of periodic waves are found in the supersonic regime: (i) smooth waves whose small amplitude limit is described by harmonic theory, and (ii) waves with sharp troughs and smooth crests of the potential with the electrons accumulating in the troughs.