Kilo-Tesla axial magnetic field generation with high intensity spin and orbital angular momentum beams

TL;DR

This paper investigates how ultra-high intensity laser beams with angular momentum generate strong axial magnetic fields in plasma, combining analytic models with 3D simulations to understand the effect's dependence on laser parameters.

Contribution

It introduces new models for magnetic field profiles and decay, and compares effects of different laser beam polarizations on magnetic field generation.

Findings

Magnetic field strength is independent of plasma density.

Field strength strongly depends on laser beam waist.

Analytic models align with 3D particle-in-cell simulation results.

Abstract

Absorption of angular momentum from a high intensity laser pulse can lead to the generation of strong axial magnetic fields in plasma. The effect, known as the inverse Faraday effect can generate kilo-Tesla strength, multi-picosecond, axial magnetic fields extending over hundreds of microns in underdense plasma. In this paper we explore the effect with ultra-high intensity circularly polarized Gaussian beams and linearly polarized orbital angular momentum beams comparing analytic expressions with 3D particle-in-cell simulations. We develop a model for the transverse magnetic field profiles, introduce a new model for the temporal decay, and show that while the magnetic field strength is independent of plasma density, it has a strong dependence on the laser beam waist.