Energy-chirp compensation in laser wakefield accelerators

TL;DR

This paper introduces a method using longitudinal density tailoring in laser wakefield accelerators to significantly reduce energy spread, converting broadband beams into quasi-monoenergetic ones with high charge, supported by experiments and simulations.

Contribution

It presents a novel technique of density tailoring to compensate energy chirp, achieving lower energy spread in laser wakefield accelerators.

Findings

Reduced energy spread to less than 10% with high charge

Supported by experimental data and 3D PIC simulations

Potential for sub-percent energy spread in certain regimes

Abstract

The energy spread in laser-wakefield accelerators is primarily limited by the energy-chirp introduced during the injection and acceleration processes. Here we propose and demonstrate the use of longitudinal density tailoring to adapt the accelerating fields and reduce the chirp at the end of the accelerator. Experimental data supported by 3D PIC simulations show that broadband electron beams can be converted to quasi-monoenergetic beams of less than 10% energy spread while maintaining a high charge of more than 120 pC. In the linear and quasi-linear regimes of wakefield acceleration, the method could provide even lower, sub-percent level, energy spread.