Underdense relativistically thermal plasma produced by magnetically assisted direct laser acceleration

TL;DR

This paper presents a novel method to generate volumetric relativistically thermal plasma at accessible densities using dual laser pulses and magnetic fields, enabling new experimental studies of high-energy-density plasmas.

Contribution

The authors introduce a new approach combining two laser pulses and magnetic fields to produce bulk relativistically thermal plasma at gas-jet densities, demonstrated through simulations and theory.

Findings

Achieved multi-MeV electron energies in a significant plasma volume.

Electron momentum distribution is 2D-isotropic and persists post-interaction.

Method enables experimental access to high-energy-density plasma regimes.

Abstract

We introduce the first approach to volumetrically generate relativistically thermal plasma at gas-jet--accessible density. Using fully kinetic simulations and theory, we demonstrate that two stages of direct laser acceleration driven by two laser pulses in an applied magnetic field can heat a significant plasma volume to multi-MeV average energy. The highest-momentum feature is 2D-isotropic, persists after the interaction, and includes the majority of electrons, enabling experimental access to bulk-relativistic, high-energy-density plasma in an optically diagnosable regime for the first time.