One-dimensional PIC Simulation of Induced Compton Scattering in Magnetized Electron-Positron Pair Plasma

TL;DR

This study uses one-dimensional PIC simulations to explore how induced Compton scattering behaves in a magnetized electron-positron pair plasma, confirming theoretical predictions of two fluctuation modes and their growth rates.

Contribution

First simulation-based confirmation of charged and neutral mode behaviors and growth rates in magnetized pair plasmas during induced Compton scattering.

Findings

Charged mode exhibits oppositely fluctuating electron and positron densities.

Neutral mode shows in-phase fluctuations with charge Debye-screened.

Linear growth rates match analytical estimates, with some cases saturating early.

Abstract

We investigate induced Compton scattering of a circularly polarized Alfv\'en wave propagating in a magnetized electron-positron pair plasma using one-dimensional Particle-in-Cell (PIC) simulations. In this system, two distinct modes of density fluctuations, referred to as the charged mode and the neutral mode, are theoretically expected to arise through parametric instabilities. Our simulations confirm these predictions: in the charged mode, the electron and positron densities fluctuate oppositely (Langmuir-like), while in the neutral mode, the charge is Debye-screened and both species fluctuate in phase (acoustic-like). The linear growth rates obtained from the simulations are in good agreement with analytical estimates for both modes. We also find that, in some cases, the linear growth saturates before full scattering occurs, allowing the incident wave to propagate without significant attenuation. Our results allow us to determine whether induced Compton scattering grows linearly in magnetized pair plasmas, offering a foundation for studies of fast radio bursts and laser-plasma experiments.