Evolution of laser-driven magnetic fields from proton tomography

TL;DR

This paper uses proton tomography to study the time evolution of laser-driven magnetic fields in plasma, revealing a transition from localized to extended fields and comparing measurements with simulations.

Contribution

It provides the first detailed temporal characterization of self-generated magnetic fields using multi-view proton tomography in laser-plasma interactions.

Findings

Magnetic fields transition from near-target to extended coronal regions over time.

Magnetic flux measurements align well with extended-MHD simulations.

Field structure predictions require further refinement in transport models.

Abstract

Self-generated magnetic fields are commonly produced in high-power laser-plasma interactions. These fields can inhibit plasma heat-flow which makes them important in inertial fusion and controlled laboratory astrophysics experiments. In this work, we characterize the time evolution of self-generated magnetic fields using multi-view proton tomography at two timings. Tomographic reconstructions of the magnetic field show a clear transition from fields located close to the target at early time to more extended coronal fields at later time. The tomographic inversion and mesh radiography also enable a direct measurement of the magnetic-flux evolution. Comparisons with extended-MHD simulations show only moderate agreement in field structure, but good agreement in magnetic flux. This suggests that the field generation model is largely correct under these conditions, while the magnetic transport model requires additional development to reproduce the observed field structure.