Optimizing laser coupling, matter heating, and particle acceleration from solids using multiplexed ultraintense lasers

TL;DR

This paper explores how overlapping multiple ultraintense lasers on solid targets enhances particle acceleration and heating, using experiments and simulations to understand the underlying magnetic reconnection mechanisms.

Contribution

It demonstrates that multi-beam laser configurations can significantly improve laser-target coupling and particle acceleration, revealing magnetic reconnection as a key process.

Findings

Overlapping two lasers increases hot electron generation and ion acceleration.

Magnetic reconnection driven by self-induced magnetic fields boosts electron energization.

Additional laser beams can further enhance coupling effects.

Abstract

Realizing the full potential of ultrahigh-intensity lasers for particle and radiation generation will require multi-beam arrangements due to technology limitations. Here, we investigate how to optimize their coupling with solid targets. Experimentally, we show that overlapping two intense lasers in a mirror-like configuration onto a solid with a large preplasma can greatly improve the generation of hot electrons at the target front and ion acceleration at the target backside. The underlying mechanisms are analyzed through multidimensional particle-in-cell simulations, revealing that the self-induced magnetic fields driven by the two laser beams at the target front are susceptible to reconnection, which is one possible mechanism to boost electron energization. In addition, the resistive magnetic field generated during the transport of the hot electrons in the target bulk tends to improve their collimation. Our simulations also indicate that such effects can be further enhanced by overlapping more than two laser beams.