Laboratory simulation of field aligned currents in experiment on laser-produced plasma interacting with magnetic dipole

TL;DR

This study demonstrates the first laboratory simulation of field aligned currents (FAC) in laser-produced plasma interacting with a magnetic dipole, revealing features similar to Earth's magnetospheric currents and their dependence on conductive conditions.

Contribution

It provides the first experimental observation of FAC in a lab setting and links laboratory results to Earth's magnetospheric phenomena, including a model of electric potential generation.

Findings

FAC observed only with conductive dipole cover

FAC features resemble Earth's Region-1 currents

Model of electric potential generation matches experimental data

Abstract

In an experiment on a magnetic dipole interacting with a laser-produced plasma the generation of an intense field aligned current (FAC) system was observed for the first time in a laboratory. The detailed measurements of the total value and local current density, of the magnetic field at the poles and in the equatorial magnetopause, and particular features of electron motion in the current channels revealed its similarity to the Region-1 current system in the Earth magnetosphere. Such currents were found to exist only if they can close via conductive cover of the dipole. Comparison of conductive and dielectric cases revealed specific magnetic features produced by FACand their connection with electric potential generated in the equatorial part of the magnetopause. To interpret the data we consider a model of electric potential generation in the boundary layer which agrees with experiment and with measurements of the Earth transpolar potential in the absence of an interplanetary magnetic field as well. The results could be of importance for the investigation of Mercury as a magnetic disturbance due to FAC could be especially large because of the small size of the Hermean magnetosphere.