Plasmoid ejection and secondary current sheet generation from magnetic reconnection in laser-plasma interaction

TL;DR

This study investigates magnetic reconnection in laser-plasma interactions, revealing plasmoid ejection, secondary current sheet formation, and electron acceleration with power-law energy distribution, advancing understanding of plasma dynamics.

Contribution

It introduces a new experimental setup with dual target layers to better model magnetotail reconnection and observes novel phenomena like plasmoid ejection and secondary current sheet formation.

Findings

Observation of fan-like electron outflows and collimated jets.

Power-law energy distribution of high-energy electrons.

Formation of secondary current sheet induced by plasmoid ejection.

Abstract

Reconnection of the self-generated magnetic fields in laser-plasma interaction was first investigated experimentally by Nilson {\it et al.} [Phys. Rev. Lett. 97, 255001 (2006)] by shining two laser pulses a distance apart on a solid target layer. An elongated current sheet (CS) was observed in the plasma between the two laser spots. In order to more closely model magnetotail reconnection, here two side-by-side thin target layers, instead of a single one, are used. It is found that at one end of the elongated CS a fan-like electron outflow region including three well-collimated electron jets appears. The ($>1$ MeV) tail of the jet energy distribution exhibits a power-law scaling. The enhanced electron acceleration is attributed to the intense inductive electric field in the narrow electron dominated reconnection region, as well as additional acceleration as they are trapped inside the rapidly moving plasmoid formed in and ejected from the CS. The ejection also induces a secondary CS.