Kinetic equation for nonlinear wave-particle interaction: solution properties and asymptotic dynamics

TL;DR

This paper analyzes a kinetic equation modeling nonlinear wave-particle interactions, showing solutions tend to a constant distribution faster than traditional quasi-linear theory, with numerical confirmation.

Contribution

It introduces a detailed analysis of the solution properties and asymptotic behavior of a kinetic equation for nonlinear wave-particle interactions, highlighting faster evolution compared to existing theories.

Findings

Solutions tend to a constant distribution over time

The distribution flattens faster than in quasi-linear plasma theory

Numerical simulations confirm the theoretical results

Abstract

We consider a kinetic equation describing evolution of a particle distribution function in a system with nonlinear wave-particle interactions (trappings into a resonance and nonlinear scatterings). We study properties of its solutions and show that the only stationary solution is a constant, and that all solutions with smooth initial conditions tend to constant as time grows. The resulting flattening of the distribution function in the domain of nonlinear interactions is similar to one described by the quasi-linear plasma theory, but the distribution evolves much faster. The results are confirmed numerically for a model problem.