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

J Von Der Linden,L Willingale,J Peebles,A Link,Hui Chen,M R Edwards,G Fiksel,D Mastrosimone

doi:10.1063/5.0057582

Abstract

Creating a 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 toward a laboratory pair plasma, we have demonstrated an effective confinement of multi-MeV electrons inside a pulsed-power-driven 13 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 ≤2.5 MeV electrons confined in the mirror for ∼1 ns. With a source of 1012 electron-positron pairs at comparable energies, this magnetic mirror would confine a relativistic pair plasma with Lorentz factor γ∼6 and magnetization σ∼40.

Highlights

Pair plasma of positrons and electrons behaves drastically different from electron-ion plasmas due to their unity mass ratio.[1]
As a step toward a laboratory pair plasma, we have demonstrated an effective confinement of multi-MeV electrons inside a pulsed-power-driven 13 T magnetic mirror field with a mirror ratio of 2.6
The broad angular divergence of electrons leaving the target results in axial losses measured by the electron-positron-proton spectrometers (EPPS) even when no magnetic field is applied

Summary

INTRODUCTION

Pair plasma of positrons and electrons behaves drastically different from electron-ion plasmas due to their unity mass ratio.[1]. Positrons with energies of tens to hundreds of eV can be harnessed with continuous fluxes of 109 sÀ1 through the capture of fission neutrons and moderation[15] and in ls pulses of 1:5 Â 105 positrons with 40 Hz repetition rates through electron-target interactions and moderation at radio frequency accelerator facilities.[16] Short pulse ($10 ps) laser-target interactions generate large numbers of multi-MeV positrons,[17] up to a 1012. This favors lasermatter interactions as source for relativistic pair plasma experiments.[5]. 2.5 MeV electrons for a nanosecond in the 13 T mirror field

MIRROR DESIGN

EXPERIMENT SETUP

RESULTS AND ANALYSIS

CONCLUSION