Electrostatic and thermal fluctuations are the source of magnetic fields in unmagnetized inhomogeneous plasmas

TL;DR

This paper demonstrates how electron thermal fluctuations and inhomogeneities in plasma can generate and destabilize low-frequency magnetic fields, relevant to laser-induced plasmas and astrophysical conditions.

Contribution

It introduces a theoretical model showing the coupling of thermal fluctuations with ion acoustic modes to produce unstable magnetic fields in unmagnetized inhomogeneous plasmas.

Findings

Electron thermal fluctuations couple with ion acoustic modes.

Parallel temperature and density gradients lead to magnetic field instability.

Model applied to laser-induced plasma scenarios.

Abstract

It is pointed out that electron thermal fluctuations can couple with the ion acoustic mode in an inhomogeneous plasma to generate a low frequency ion time scale electromagnetic wave. This electromagnetic wave can become unstable if the temperature and density gradients are parallel to each other which can be the case in laser-plasmas similar to stellar cores. The comparisons of the present theoretical model with the previous investigations are also presented. The final result is applied to a classical laser induced plasma for illustration.