Fast magnetic field annihilation in the relativistic collisionless regime driven by two ultra-short high-intensity laser pulses

TL;DR

This paper demonstrates how two ultra-short high-intensity laser pulses create a magnetic quadrupole in collisionless plasma, leading to magnetic field annihilation and energy transfer to electrons in the ultrarelativistic regime.

Contribution

It introduces a novel simulation-based analysis of magnetic field annihilation driven by ultra-short laser pulses in collisionless plasma.

Findings

Magnetic quadrupole structures form during laser-plasma interaction.

Magnetic field annihilation occurs in the ultrarelativistic regime.

Magnetic energy converts into electron kinetic energy within a current sheet.

Abstract

The magnetic quadrupole structure formation during the interaction of two ultra-short high power laser pulses with a collisionless plasma is demonstrated with 2.5-dimensional particle-in-cell simulations. The subsequent expansion of the quadrupole is accompanied by magnetic field annihilation in the ultrarelativistic regime, when the magnetic field can not be sustained by the plasma current. This results in a dominant contribution of the displacement current exciting a strong large scale electric field. This field leads to the conversion of magnetic energy into kinetic energy of accelerated electrons inside the thin current sheet.