Disruption of current filaments and isotropization of magnetic field in counter-streaming plasmas

TL;DR

This paper investigates how a resonance between ions and a drift-kink mode destabilizes current filaments in counter-streaming plasmas, leading to magnetic field isotropization and shock formation, validated through analytical and simulation methods.

Contribution

It identifies a resonance mechanism that disrupts current filaments and promotes magnetic isotropization, advancing understanding of collisionless shock dynamics.

Findings

Resonance causes filament deformation and breaking.

Drift-kink mode dominates flow slowdown.

Magnetic field becomes more isotropic.

Abstract

We study the stability of current filaments produced by the Weibel, or current filamentation, instability in weakly magnetized counter-streaming plasmas. It is shown that a resonance exists between the current-carrying ions and a longitudinal drift-kink mode that strongly deforms and eventually breaks the current filaments. Analytical estimates of the wavelength, growth rate and saturation level of the resonant mode are derived and validated by three-dimensional particle-in-cell simulations. Furthermore, self-consistent simulations of counter-streaming plasmas indicate that this drift-kink mode is dominant in the slow down of the flows and in the isotropization of the magnetic field, playing an important role in the formation of collisionless shocks.