Effects of kappa distribution function on Landau damping in electrostatic Vlasov simulation

TL;DR

This study investigates how non-thermal high-energy electrons, modeled by kappa distribution functions, influence Landau damping in electrostatic Vlasov simulations, revealing increased damping rates and altered wave frequencies.

Contribution

It introduces a detailed analysis of Landau damping modifications due to kappa distributions using Vlasov-Poisson simulations and compares results with plasma dispersion functions.

Findings

Increased Landau damping rate with lower kappa values.

Decreased real frequency for long wavelength limit.

Good agreement between simulation and plasma dispersion analysis.

Abstract

Effects of non-thermal high-energy electrons on Langmuir wave-particle interaction are investigated by an initial value approach. A Vlasov-Poisson simulation is employed which is based on the splitting scheme by Cheng and Knorr [Cheng, C.Z. and G. Knorr, 1976: J. Comput. Phys. 22, 330-351.]. The kappa distribution function is taken as an example of non-thermal electrons. The modification is manifested as an increase in the Landau damping rate and a decrease in the real frequency for a long wavelength limit. A part of the analyses by the modified plasma dispersion function [Summers, D. and R.M.Thorne, 1991: Phys. Fluids, B 3, 1835-1847.] is reproduced for $\kappa = 2,3$ and 6. The dispersion relation from the initial value simulation and the plasma dispersion function compare favorably.