Enhanced Proton Acceleration via Petawatt Laguerre-Gaussian Lasers

TL;DR

This paper presents a novel all-optical method using Laguerre-Gaussian lasers to produce highly collimated, high-energy proton beams more efficiently than traditional Gaussian laser schemes, with potential for medical and fusion applications.

Contribution

The study introduces a new collimation mechanism for proton acceleration using a single femtosecond LG laser, enhancing energy and beam quality without complex target fabrication.

Findings

Proton energy increased by 60% to 35 MeV with LG laser.

Beam divergence significantly reduced compared to Gaussian schemes.

Particle-in-cell simulations elucidate the focusing and collimation process.

Abstract

High-energy, high-flux collimated proton beams with high repetition rates are critical for applications such as proton therapy, proton radiography, high-energy-density matter generation, and compact particle accelerators. However, achieving proton beam collimation has typically relied on complex and expensive target fabrication or precise control of auxiliary laser pulses, which poses significant limitations for high-repetition applications. Here, we demonstrate an all-optical method for collimated proton acceleration using a single femtosecond Laguerre-Gaussian (LG) laser with an intensity exceeding 1020 W/cm2 irradiating a simple planar target. Compared to conventional Gaussian laser-driven schemes, the maximum proton energy is enhanced by 60% (reaching 35 MeV) and beam divergence is much reduced. Particle-in-cell simulations reveal that a plasma jet is initially focused by the hollow electric sheath field of the LG laser, and then electrons in the jet are further collimated by self-generated magnetic fields. This process amplifies the charge-separation electric field between electrons and ions, leading to increased proton energy in the longitudinal direction and improved collimation in the transverse direction. This single-LG-laser-driven collimation mechanism offers a promising pathway for high-repetition, high-quality proton beam generation, with broad potential applications including proton therapy and fast ignition in inertial confinement fusion.