Relativistic magnetic reconnection driven by a laser interacting with a micro-scale plasma slab

Longqing Yi,Alexander Pukhov,Baifei Shen,Tünde Fülöp

doi:10.1038/s41467-018-04065-3

Abstract

Magnetic reconnection (MR) is a fundamental plasma process associated with conversion of the magnetic field energy into kinetic plasma energy, which is invoked to explain many non-thermal signatures in astrophysical events. Here we demonstrate that ultrafast relativistic MR in a magnetically dominated regime can be triggered by a readily available (TW-mJ-class) laser interacting with a micro-scale plasma slab. Three-dimensional (3D) particle-in-cell (PIC) simulations show that when the electrons beams excited on both sides of the slab approach the end of the plasma, MR occurs and it gives rise to efficient energy dissipation that leads to the emission of relativistic electron jets with cut-off energy ~12 MeV. The proposed scenario allows for accessing an unprecedented regime of MR in the laboratory, and may lead to experimental studies that can provide insight into open questions such as reconnection rate and particle acceleration in relativistic MR.

Highlights

Magnetic reconnection (MR) is a fundamental plasma process associated with conversion of the magnetic field energy into kinetic plasma energy, which is invoked to explain many nonthermal signatures in astrophysical events
Most of the previous laser-driven MR studies are focused on the non-relativistic case, and the ratio of the plasma thermal and magnetic energy density, β, is typically high (β > 1)[33]
It has been reported that magnetically dominated MR can be achieved by a double-turn Helmholtz capacitor-coil target[38], but this approach is very difficult to extend to the relativistic regime because it requires a kJclass laser system

Summary

Introduction

Magnetic reconnection (MR) is a fundamental plasma process associated with conversion of the magnetic field energy into kinetic plasma energy, which is invoked to explain many nonthermal signatures in astrophysical events. 1, where B0 is the magnetic field strength, me is the electron mass, n is the plasma density, and c is the vacuum light velocity In such environments, magnetic reconnection (MR) operating in the relativistic regime, plays a key role in the transfer of large amounts of magnetic to kinetic energy via field dissipation[1,2,3]. Due to difficulties in achieving the extreme magnetic energy densities that are required to observe relativistic MR in laboratory environments, previous experimental studies investigated mainly the non-relativistic regime (σ < 1) These include experimental observation of MR in tokamaks[19] or dedicated experiments, such as MRX (Magnetic Reconnection Experiment)[20]. In spite of the remarkable progress that has been made, relativistic MR in low-β environments (β < 1), which is closely related to the interpretation of many space plasma measurements and astronomical observations[39], has not been thoroughly studied

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