# Generation of controllable plasma wakefield noise in particle-in-cell simulations

## TL;DR

This paper introduces a new method to generate controllable plasma wakefield noise in particle-in-cell simulations, enabling more accurate modeling of beam-plasma instabilities by reducing unrealistic initial noise levels.

## Contribution

A novel technique using randomly placed charged rods is proposed to produce adjustable wakefield noise without parasitic effects in simulations.

## Key findings

- Method effectively controls noise amplitude in simulations.
- No parasitic Cherenkov radiation observed.
- Improves accuracy of beam-plasma instability modeling.

## Abstract

Numerical simulations of beam-plasma instabilities may produce quantitatively incorrect results because of unrealistically high initial noise from which the instabilities develop. Of particular importance is the wakefield noise, the potential perturbations that have a phase velocity which is equal to the beam velocity. Controlling the noise level in simulations may offer the possibility of extrapolating simulation results to the more realistic low-noise case. We propose a novel method for generating wakefield noise with a controllable amplitude by randomly located charged rods propagating ahead of the beam. We also illustrate the method with particle-in-cell simulations. The generation of this noise is not accompanied by parasitic Cherenkov radiation waves.