Weakly nonlinear ion sound waves in gravitational systems

TL;DR

This paper investigates weakly nonlinear ion sound waves in a gravitational plasma, revealing wave growth due to energy flux conservation, modeled by a modified KdV equation, with analytical and PIC simulation validation.

Contribution

It introduces a modified KdV model for ion sound waves in gravitational fields and compares analytical solutions with PIC simulations, accounting for deviations from neutrality.

Findings

Wave amplitude increases due to energy flux conservation.

Modified KdV equation effectively models wave behavior.

Simulation results agree with analytical predictions.

Abstract

Ion sound waves are studied in a plasma subject to gravitational field. Such systems are interesting by exhibiting a wave growth that is a result of energy flux conservation in inhomogeneous systems. The increasing wave amplitude gives rise to an enhanced interaction between waves and plasma particles that can be modeled by a modified Korteweg-de Vries equation. Analytical results are compared with numerical Particle-in-Cell simulations of the problem. Our code assumes isothermally Boltzmann distributed electrons while the ion component is treated as a collection of individual particles interacting through collective electric fields. Deviations from quasi neutrality are allowed for.