Particle-in-Cell simulation of two-dimensional electron velocity shear driven instability in relativistic domain

TL;DR

This paper uses Particle-in-Cell simulations to explore how relativistic electron flows become unstable, revealing different behaviors in weak and strong relativistic regimes, including turbulence and electrostatic oscillations.

Contribution

It provides the first detailed PIC simulation analysis of relativistic shear-driven instabilities in two-dimensional electron flows, highlighting differences from non-relativistic models.

Findings

Weak relativistic flows develop Kelvin-Helmholtz instability similar to EMHD predictions.

Strong relativistic flows exhibit electrostatic oscillations due to compressibility effects.

Both regimes lead to turbulence with broad power-law spectra.

Abstract

We carry out Particle-in-Cell (PIC) simulations to study the instabilities associated with a 2-D sheared electron flow configuration against a neutralizing background of ions. Both weak and strong relativistic flow velocities are considered. In the weakly relativistic case, we observe the development of electromagnetic Kelvin Helmholtz instability with similar characteristics as that predicted by the electron Magnetohydrodynamic (EMHD) model. On other hand, in strong relativistic case the compressibility effects of electron fluid dominate and introduce upper hybrid electrostatic oscillations transverse to the flow which are very distinct from EMHD fluid behaviour. In the nonlinear regime, both weak and strong relativistic cases lead to turbulence with broad power law spectrum.