Confinement of relativistic electrons in a magnetic mirror en route to a magnetized relativistic pair plasma

TL;DR

This study demonstrates the effective confinement of relativistic electrons in a magnetic mirror, advancing the potential for laboratory creation of magnetized relativistic pair plasmas relevant to energetic astrophysical phenomena.

Contribution

The paper presents the first experimental demonstration of confining multi-MeV electrons in a pulsed magnetic mirror, paving the way for laboratory studies of relativistic pair plasmas.

Findings

Electrons with energies up to 2.5 MeV are confined for about 1 ns.

Magnetic mirror with a ratio of 2.6 effectively traps relativistic electrons.

Potential to confine relativistic pair plasmas with Lorentz factor ~6 and magnetization ~40.

Abstract

Creating magnetized relativistic pair plasma in the laboratory would enable the exploration of unique plasma physics relevant to some of the most energetic events in the universe. As a step towards a laboratory pair plasma, we have demonstrated effective confinement of multi-$\mathrm{MeV}$ electrons inside a pulsed-power-driven $13$ $\mathrm{T}$ magnetic mirror field with a mirror ratio of $2.6$. The confinement is diagnosed by measuring the axial and radial losses with magnetic spectrometers. The loss spectra are consistent with $\leq 2.5$ $\mathrm{MeV}$ electrons confined in the mirror for $\sim 1$ $\mathrm{ns}$. With a source of $10^{12}$ electron-positron pairs at comparable energies, this magnetic mirror would confine a relativistic pair plasma with Lorentz factor $\gamma \sim 6$ and magnetization $\sigma \sim 40$.