Note on quantitatively correct simulations of the kinetic beam-plasma instability

TL;DR

This paper emphasizes the importance of using a large number of model particles in simulations of the kinetic beam-plasma instability to achieve quantitative accuracy, highlighting how particle count scales with growth rate.

Contribution

It demonstrates that the number of particles needed scales inversely with the growth rate, providing guidance for accurate cloud-in-cell simulations of the instability.

Findings

Large particle numbers are necessary for accurate simulations.

Particle count scales inversely with the growth rate.

Resonance occurs only within a narrow velocity interval.

Abstract

A large number of model particles is shown necessary for quantitatively correct simulations of the kinetic beam-plasma instability with the clouds-in-cells method. The required number of particles scales inversely with the expected growth rate, as in the kinetic regime only a narrow interval of beam velocities is resonant with the wave.