Exact hybrid-Vlasov equilibria for sheared plasmas with in-plane and out-of-plane magnetic field

TL;DR

This paper derives exact stationary solutions for the hybrid Vlasov-Maxwell system in sheared plasma flows, providing detailed analysis of distribution functions and potential applications in plasma wave and instability studies.

Contribution

It presents the first exact hybrid Vlasov-Maxwell equilibria for sheared plasmas with in-plane and out-of-plane magnetic fields, extending previous models.

Findings

Distribution functions significantly depart from thermodynamic equilibrium in shear regions.

Analytical and numerical characterization of temperature anisotropy and gyrotropy.

Hybrid equilibria serve as stable initial states for studying plasma instabilities.

Abstract

The hybrid Vlasov-Maxwell system of equations is suitable to describe a magnetized plasma at scales of the order of or larger than proton kinetic scales. An exact stationary solution is presented by revisiting previous results with a uniform-density shear flow, directed either parallel or perpendicular to a uniform magnetic field, and by adapting the solution to the hybrid Vlasov-Maxwell model. A quantitative characterization of the equilibrium distribution function is provided by studying both analytically and numerically the temperature anisotropy and gyrotropy and the heat flux. In both cases, in the shear region, the velocity distribution significantly departs from local thermodynamical equilibrium. A comparison between the time behavior of the usual "fluid-like" equilibrium shifted Maxwellian and the exact stationary solutions is carried out by means of numerical simulations of the hybrid Vlasov-Maxwell equations. These hybrid equilibria can be employed as an unperturbed states for numerous problems which involve sheared flows, such as the wave propagation in inhomogeneous background and the onset of the Kelvin-Helmholtz instability.