Magnetic field generation in laser-solid interactions at strong-field QED relevant intensities

TL;DR

This study uses 2D particle-in-cell simulations to explore magnetic field generation in ultra-intense laser-solid interactions at intensities relevant to future laser facilities, revealing significant field strengths and energy conversion effects.

Contribution

It introduces a model for the evolution and scaling of surface magnetic fields with laser intensity, aiding future experimental planning.

Findings

Fields up to 0.1 MT generated by relativistic electrons

Approximately 38% of energy converts to high-energy photons at high intensities

The model predicts magnetic field strengths for next-generation laser facilities

Abstract

Magnetic field generation in ultra-intense laser-solid interactions is studied over a range of laser intensities relevant to next-generation laser facilities ($a_0 = 50-500$) using 2D particle-in-cell simulations. It is found that fields on the order of 0.1 MT (1 GigaGauss) may be generated by relativistic electrons traveling along the surface of the target. However a significant fraction of the energy budget is converted to high-energy photons, ~38% at $a_0=500$, greatly reducing the available energy for field generation. A model for the evolution of the target-surface fields and their scaling with $a_0$ is developed using laser parameters and assumed values for the average radial electron velocity and reflectivity. The model and empirical scaling allow for the estimation of field strengths on the next generation of laser facilities, a necessary component to the proposal of any future magnetized experiment.