Inefficient magnetic-field amplification in supersonic laser-plasma turbulence

TL;DR

This study presents the first laboratory realization of magnetized, turbulent, supersonic plasma with high magnetic Reynolds number, revealing that such turbulence is inefficient at significantly amplifying magnetic fields.

Contribution

The paper demonstrates the first experimental creation of magnetized, turbulent, supersonic plasma with high magnetic Reynolds number and investigates its magnetic field amplification properties.

Findings

Magnetic fields were only moderately amplified and remained dynamically insignificant.

No magnetic energy was observed at scales smaller than the outer turbulent scale.

Moderately supersonic, low-magnetic-Prandtl-number turbulence is inefficient at magnetic field amplification.

Abstract

We report a laser-plasma experiment that was carried out at the LMJ-PETAL facility and realized the first magnetized, turbulent, supersonic plasma with a large magnetic Reynolds number ($\mathrm{Rm} \approx 45$) in the laboratory. Initial seed magnetic fields were amplified, but only moderately so, and did not become dynamically significant. A notable absence of magnetic energy at scales smaller than the outer scale of the turbulent cascade was also observed. Our results support the notion that moderately supersonic, low-magnetic-Prandtl-number plasma turbulence is inefficient at amplifying magnetic fields.