MeV femtosecond electron pulses from direct-field acceleration in low density atomic gases

TL;DR

This paper demonstrates through 3D simulations that tightly focused few-cycle radially-polarized lasers in low-density gases can generate MeV electron pulses with femtosecond duration and attosecond microbunching, suitable for remote delivery.

Contribution

It introduces a novel method for producing relativistic femtosecond electron pulses with natural attosecond microbunching using low-power radially-polarized laser pulses in atomic gases.

Findings

Generation of few-MeV electrons via laser focusing in gases.

Observation of natural attosecond microbunching at relativistic energies.

Leading attosecond microbunch survives propagation, enabling remote delivery.

Abstract

Using three-dimensional particle-in-cell simulations, we show that few-MeV electrons can be produced by focusing tightly few-cycle radially-polarized laser pulses in a low-density atomic gas. In particular, it is observed that for the few-TW laser power needed to reach relativistic electron energies, longitudinal attosecond microbunching occurs naturally, resulting in femtosecond structures with high-contrast attosecond density modulations. The three-dimensional particle-in-cell simulations show that in the relativistic regime the leading pulse of these attosecond substructures survives to propagation over extended distances, suggesting that it could be delivered to a distant target, with the help of a properly designed transport beamline.