On annihilation of the relativistic electron vortex pair in collisionless plasmas

TL;DR

This paper uses computer simulations to show how magnetic field annihilation leads to the rapid destruction of relativistic electron vortex pairs in collisionless plasmas, converting magnetic energy into energetic particles and plasma waves.

Contribution

It reveals the mechanisms of vortex pair annihilation in relativistic plasmas and how vortex size and relativistic effects influence energy dissipation pathways.

Findings

Magnetic field annihilation causes rapid vortex pair dissipation.

Secondary vortex formation becomes dominant in ultrarelativistic regimes.

Vortex size relative to electron skin depth affects energy damping mechanisms.

Abstract

In contrast to hydrodynamic vortices, vortices in plasma contain an electric current circulating around the center of the vortex, which generates a magnetic field localized inside. Using computer simulations, we demonstrate that the magnetic field associated with the vortex gives rise to a mechanism of dissipation of the vortex pair in a collisionless plasma, leading to fast annihilation of the magnetic field with its energy transforming into the energy of fast electrons, secondary vortices, and plasma waves. Two major contributors to the energy damping of double vortex system, namely, magnetic field annihilation and secondary vortex formation, are regulated by the size of the vortex with respect to the electron skin depth, which scales with the electron gamma-factor, $\gamma_e$, as $R/d_e \propto \gamma_e^{1/2}$. Magnetic field annihilation appears to be dominant in mildly relativistic vortices, while for the ultrarelativistic case, secondary vortex formation is the main channel for damping of the initial double vortex system.