High quality electron beam acceleration by ionization injection in laser wakefields with mid-infrared dual-color lasers

TL;DR

This paper proposes a novel bichromatic laser ionization injection method using mid-infrared and near-infrared lasers to generate high-quality, high-charge electron beams at GeV energies with low energy spread in laser wakefield acceleration.

Contribution

It introduces a dual-color laser scheme combined with carbon dioxide as the medium to improve beam quality and reduce laser power requirements in laser wakefield acceleration.

Findings

Electron beams at GeV energies achieved with low energy spread (~1%)

High charge electron beams (tens of picocoulombs) demonstrated

Laser parameters are feasible with current technology

Abstract

For the laser wakefield acceleration, suppression of beam energy spread while keeping sufficient charge is one of the key challenges. In order to achieve this, we propose bichromatic laser ionization injection with combined laser wavelengths of $2.4\rm \mu m$ and $0.8\rm \mu m$ for wakefield excitation and for triggering electron injection via field ionization, respectively. A laser pulse at $2.4\rm \mu m$ wavelength enables one to drive an intense acceleration structure with relatively low laser power. To further reduce the requirement of laser power, we also propose to use carbon dioxide as the working gas medium, where carbon acts as the injection element. Our full three dimensional particle-in-cell simulations show that electron beams at the GeV energy level with both low energy spreads (around one percent) and high charges (several tens of picocoulomb) can be obtained by this scheme with laser parameters achievable in the near future.