Turbulent magneto-genesis in a collisionless plasma

TL;DR

This paper demonstrates how turbulence-induced electron temperature anisotropy in collisionless plasmas can trigger a Weibel instability, leading to magnetic field generation through kinetic simulations, with implications for astrophysical magneto-genesis.

Contribution

It introduces a novel kinetic simulation-based mechanism showing turbulence-driven electron anisotropy can initiate magnetic field growth via Weibel instability in collisionless plasmas.

Findings

Magnetic fields grow exponentially in turbulent, collisionless plasmas.

Electron temperature anisotropy is locally generated by turbulent flow.

The process may explain magneto-genesis in astrophysical environments.

Abstract

We investigate an efficient mechanism for generating magnetic fields in turbulent, collisionless plasmas. By using fully kinetic, particle-in-cell simulations of an initially non-magnetized plasma, we inspect the genesis of magnetization, in a nonlinear regime. The complex motion is initiated via a Taylor-Green vortex, and the plasma locally develops strong electron temperature anisotropy, due to the strain tensor of the turbulent flow. Subsequently, in a domino effect, the anisotropy triggers a Weibel instability, localized in space. In such active wave-particle interaction regions, the magnetic field seed grows exponentially and spreads to larger scales due to the interaction with the underlying stirring motion. Such a self-feeding process might explain magneto-genesis in a variety of astrophysical plasmas, wherever turbulence is present.