Electron Acceleration in a Flying-Focus Laser Wakefield Accelerator

TL;DR

This paper demonstrates novel experiments with a flying-focus laser wakefield accelerator that can accelerate electrons to relativistic energies by mitigating dephasing, supported by simulations and optical techniques.

Contribution

It introduces a new experimental approach using a sculpted laser pulse and quasi-Bessel beam to control wakefield velocity and enhance electron acceleration.

Findings

Achieved relativistic electron energies with flying-focus scheme.

Supported experimental results with optical and particle-in-cell simulations.

Demonstrated partial mitigation of dephasing in laser wakefield acceleration.

Abstract

Structured light pulses hold significant promise for their ability to overcome dephasing in laser-wakefield accelerators, that should facilitate applications in high-energy physics and XFEL. Numerical studies have shown that sculpting a pulse into a flying focus and using it to drive a wakefield can achieve dephasing-free acceleration of electrons, with gain in excess of 100\,GeV within reachable with existing laser facilities. This work reports on novel experiments using a flying-focus generated laser-wakefield accelerator to accelerate electrons to relativistic energies. The flying-focus pulse is achieved by sculpting the laser-pulse before focusing using spatio-temporal couplings and generating a quasi-Bessel beam with an axiparabola. This combination allows for the tuning of the propagation velocity of the wakefield, which, we demonstrate, has an impact on the maximum achievable electron energy. Optical and particle-in-cell simulations are used to support the data and to provide direct evidence of the partial mitigation of dephasing through this flying-focus scheme. These results are further elucidated in our companion letter [1].