Recovering the damping rates of cyclotron damped plasma waves from simulation data

TL;DR

This paper introduces a straightforward method to extract damping rates of cyclotron damped plasma waves from simulation data, validated through comparisons with theoretical predictions across various simulation setups.

Contribution

The paper presents a new, simple technique for accurately determining damping rates from plasma simulation data, improving analysis of wave damping phenomena.

Findings

Damping rates from simulations agree well with theoretical values.

Method works across different simulation dimensions and parameters.

Provides a detailed step-by-step procedure for damping rate extraction.

Abstract

Plasma waves with frequencies close to the particular gyrofrequencies of the charged particles in the plasma lose energy due to cyclotron damping. We briefly discuss the gyro-resonance of low frequency plasma waves and ions particularly with regard to particle-in-cell (PiC) simulations. A setup is outlined which uses artificially excited waves in the damped regime of the wave mode's dispersion relation to track the damping of the wave's electromagnetic fields. Extracting the damping rate directly from the field data in real or Fourier space is an intricate and non-trivial task. We therefore present a simple method of obtaining the damping rate {\Gamma} from the simulation data. This method is described in detail, focusing on a step-by-step explanation of the course of actions. In a first application to a test simulation we find that the damping rates obtained from this simulation generally are in good agreement with theoretical predictions. We then compare the results of one-, two- and three-dimensional simulation setups and simulations with different physical parameter sets.