Topology of Megagauss Magnetic Fields and of Heat-Carrying Electrons Produced in a High-Power Laser-Solid Interaction

Abstract

The intricate spatial and energy distribution of magnetic fields, self-generated during high power laser irradiation (at Iλ^{2}∼10^{13}-10^{14} W.cm^{-2}.μm^{2}) of a solid target, and of the heat-carrying electron currents, is studied in inertial confinement fusion (ICF) relevant conditions. This is done by comparing proton radiography measurements of the fields to an improved magnetohydrodynamic description that fully takes into account the nonlocality of the heat transport. We show that, in these conditions, magnetic fields are rapidly advected radially along the target surface and compressed over long time scales into the dense parts of the target. As a consequence, the electrons are weakly magnetized in most parts of the plasma flow, and we observe a reemergence of nonlocality which is a crucial effect for a correct description of the energetics of ICF experiments.

Detailed characterization of laser-produced astrophysically-relevant jets formed via a poloidal magnetic nozzle

“…This is possible since the, order 100 T, selfgenerated B-fields (e.g. Biermann battery, ∇n e × ∇T e ) do not influence the plasma anymore as they are confined to high strength [35,36] at < 0.5 mm from the target surface, i.e. over very short scales compared to the typical plasma expansion scale.…”

Incorporating kinetic effects on Nernst advection in inertial fusion simulations

“…One possible method (described in Section II) for obtaining an approximation of nonlocal Nernst with nonlocal models designed only for thermal transport has been explored by Lancia et al [53] and is used as an inspiration for the direction of this paper. Application of this technique to a nonlocal model very similar to the snb [54,55] was able to reduce discrepancies between modeling and experiments of a planar laser-solid interaction [53,56]. The role of nonlocality in magnetised transport is not a new idea and has been previously explored in a number of papers published over thirty years ago.…”

Precision Mapping of Laser-Driven Magnetic Fields and Their Evolution in High-Energy-Density Plasmas

“…The generated magnetic fields are azimuthal in their orientation [27] and grow at the expense of the electron energy [25]. Spaceand time-resolved measurements showing where in the plasma these magnetic fields exist are important because they provide a stringent test for magnetohydrodynamic (MHD) model predictions [28][29][30][31][32][33]. The challenge is to accurately map the magnetic-field spatial distribution relative to the expanding coronal plasma.…”