Pressure anisotropy and small spatial scales induced by velocity shear

TL;DR

This paper demonstrates how velocity shear in low-collisionality plasmas can induce pressure anisotropy and small spatial scales, highlighting the role of magnetic and flow strain effects through numerical simulations.

Contribution

It introduces a fluid model incorporating full pressure tensor dynamics to explain anisotropy and filamentation caused by velocity shear in plasmas.

Findings

Velocity shear induces pressure anisotropy and agyrotropy.

Magneto-elastic waves influence pressure tensor evolution.

Numerical simulations confirm the theoretical predictions.

Abstract

Non-Maxwellian metaequilibria can exist in low-collisionality plasmas as evidenced by satellite and laboratory measurements. By including the full pressure tensor dynamics in a fluid plasma model, we show that a sheared velocity field can provide an effective mechanism that makes an initial isotropic state anisotropic and agyrotropic. We discuss how the propagation of magneto-elastic waves can affect the pressure tensor anisotropization and its spatial filamentation which are due to the action of both the magnetic field and flow strain tensor. We support this analysis by a numerical integration of the nonlinear equations describing the pressure tensor evolution.