Probing the radiation-dominated regime of laser-plasma interaction in multi-beam configurations of petawatt lasers

TL;DR

This paper models how multi-beam petawatt laser configurations can induce radiation friction effects in plasma, potentially enabling experimental observation of the Inverse Faraday Effect at lower laser powers.

Contribution

It demonstrates that multi-beam setups reduce the power threshold for observing radiation reaction effects and explores the influence of beam angles and quantum recoil on magnetic field generation.

Findings

Multi-beam configurations lower the power needed to detect magnetic fields.

Optimal beam crossing angles are around 10 degrees for maximum effect.

Quantum recoil significantly suppresses the magnetic field, but effects remain detectable.

Abstract

We model numerically the ultrarelativistic dynamics of a dense plasma microtarget in a focus of several intersecting femtosecond laser pulses of multi-petawatt power each. The aim is to examine perspective future experimental approaches to the search of the Inverse Faraday Effect induced by radiation friction. We show that multi-beam configurations allow lowering the single beam peak laser power required to generate a detectable quasi-static longitudinal magnetic field excited due to the radiation reaction force. The effect is significant at angles around $10^{\rm o}$ between the beam propagation axes, almost vanishes when the angle exceeds $20^{\rm o}$, and remains rather stable with respect to variations of relative phases and amplitudes of the beams. Quantum recoil accounted within semi-classical approach is shown to considerably suppress the longitudinal magnetic field, which however remains sizable. We conclude that using four infrared femtosecond linearly polarized pulses, 15 petawatt power each, crossing at angles $\approx 10^{\rm o}$, the radiation-dominated regime of laser-plasma interaction can be experimentally demonstrated.