K. Weichman, J. Palastro, A. Robinson, R. Bingham, and A. Arefiev, "Underdense relativistically thermal plasma produced by magnetically assisted direct laser acceleration", Phys. Rev. Research 4, L042017 (2022).
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.