Lepton-driven Non-resonant Streaming Instability

TL;DR

This paper investigates the non-resonant streaming instability driven by different particle species using kinetic simulations, revealing detailed characteristics of the instability relevant for space, astrophysical, and laboratory plasma environments.

Contribution

It extends the understanding of NRSI by analyzing electron and mixed species-driven instabilities with kinetic simulations, beyond traditional ion-current models.

Findings

Characterized growth rates and spectra of unstable modes.

Determined magnetic field saturation levels.

Analyzed helicity of the modes.

Abstract

A strong super-Alfv\'{e}nic drift of energetic particles (or cosmic rays, CRs) in a magnetized plasma can amplify the magnetic field significantly through non-resonant streaming instability (NRSI). While the traditional analysis is done for an ion current, here we use kinetic particle-in-cell simulations to study how the NRSI behaves when it is driven by electrons or by a mixture of electrons and positrons. In particular, we characterize growth rate, spectrum, and helicity of the unstable modes, as well the level of magnetic field at saturation. Our results are potentially relevant for several space/astrophysical environments (e.g, electron strahl in the solar wind, at oblique non-relativistic shocks, around pulsar wind nebulae) and also in laboratory experiments.