# Electron-magnetohydrodynamic simulations of electron scale current sheet dynamics in the Vineta.II guide field reconnection experiment

## TL;DR

This paper presents 3D EMHD simulations of electron current sheet dynamics in a setup similar to the Vineta.II experiment, revealing the formation of elongated sheets and electromagnetic fluctuations driven by electron shear flow instability.

## Contribution

The study demonstrates that electron dynamics alone can account for current sheet formation and electromagnetic fluctuations, aligning simulation results with experimental observations.

## Key findings

- Formation of elongated electron scale current sheets.
- Electromagnetic fluctuations exhibit broadband spectra with power-law distribution.
- Electron shear flow instability drives electromagnetic fluctuations.

## Abstract

Three dimensional electron-magnetohydrodynamic (EMHD) simulations of electron current sheet dynamics in a background of stationary and unmagnetized ions and the subsequent generation of electromagnetic fluctuations are carried out. The physical parameters and initial magnetic configuration in the simulations are chosen to be similar to those in the \textsc{Vineta}.II magnetic reconnection experiment. Consistent with the experimental results, our 3D EMHD simulations show the formation of an elongated electron scale current sheet together with the excitation of electromagnetic fluctuations within this sheet. The fluctuations in the simulations are generated by an electron shear flow instability growing on the in-plane (perpendicular to the direction of the main current in the sheet) electron shear flow (or current) developed during the current sheet evolution. Similar to the experiments, the magnetic field fluctuations perpendicular to the guide magnetic field exhibit a broadband frequency spectrum following a power law and a positive correlation with the axial current density. Although the experimental results show that ions influence the spectral properties of the fluctuations, the simulations suggest that the electron dynamics, even in the absence of ion motion, primarily determines the formation of the current sheet and the generation of electromagnetic fluctuations observed in the experiments.