Radiation emission in laser-wakefields driven by structured laser pulses with orbital angular momentum

TL;DR

This paper introduces a novel laser-wakefield configuration using structured laser pulses with orbital angular momentum, enabling higher energy X-ray emission and independent tunability of photon energy through 3D simulations.

Contribution

It demonstrates, via detailed 3D simulations, a new method to enhance and tune X-ray emission in laser-wakefield accelerators using Laguerre-Gaussian pulses with orbital angular momentum.

Findings

Increased X-ray energy emission compared to traditional setups.

X-ray photon energy can be tuned independently of plasma parameters.

Helical laser-driven motion dominates radiation emission.

Abstract

High-intensity X-ray sources are invaluable tools, enabling experiments at the forefront of our understanding of materials science, chemistry, biology, and physics. Laser-plasma electron accelerators are sources of high-intensity X-rays, as electrons accelerated in wakefields emit short-wavelength radiation due to betatron oscillations. While applications such as phase-contrast imaging with these betatron sources have already been demonstrated, others would require higher photon number and would benefit from increased tunability. In this paper we demonstrate, through detailed 3D simulations, a novel configuration for a laser-wakefield betatron source that increases the energy of the X-ray emission and also provides increased flexibility in the tuning of the X-ray photon energy. This is made by combining two Laguerre-Gaussian pulses with non-zero net orbital angular momentum, leading to a rotation of the intensity pattern, and hence, of the driven wakefields. The helical motion driven by the laser rotation is found to dominate the radiation emission, rather than the betatron oscillations. Moreover, the radius of this helical motion can be controlled through the laser spot size and orbital angular momentum indexes, meaning that the radiation can be tuned fully independently of the plasma parameters.