Bayesian Optimization of a Laser-Plasma Accelerator.

Sören Jalas,Matthias Schnepp,Lars Hübner,Remi Lehe,Manuel Kirchen,Andreas R Maier,Philipp Messner,Paul Winkler,Julian Dirkwinkel

doi:10.1103/physrevlett.126.104801

Abstract

Generating high-quality laser-plasma accelerated electron beams requires carefully balancing a plethora of physical effects and is therefore challenging-both conceptually and in experiments. Here, we use Bayesian optimization of key laser and plasma parameters to flatten the longitudinal phase space of an ionization-injected electron bunch via optimal beam loading. We first study the concept with particle-in-cell simulations and then demonstrate it in experiments. Starting from an arbitrary set point, the plasma accelerator autonomously tunes the beam energy spread to the subpercent level at 254MeV and 4.7 pC/MeV spectral density. Finally, we study a robust regime, which improves the stability of the laser-plasma accelerator and delivers sub-five-percent rms energy spread beams for 90% of all shots.

Highlights

Generating high-quality laser-plasma accelerated electron beams requires carefully balancing a plethora of physical effects and is challenging—both conceptually and in experiments
The plasma wave supports accelerating fields that surpass those of modern radio-frequency based machines by orders of magnitude, which has led to the demonstration of fewfemtosecond [3,4], GeV-level electron beams over only cm distances [5,6]
Generating high-brightness laser-plasma electron beams requires carefully balancing a multitude of physical effects that nonlinearly couple laser and plasma parameters

Summary

Introduction

Sören Jalas ,1,* Manuel Kirchen ,1 Philipp Messner,2,1,3 Paul Winkler,3,1 Lars Hübner,3,1 Julian Dirkwinkel ,3 Matthias Schnepp,1 Remi Lehe,4 and Andreas R. Generating high-quality laser-plasma accelerated electron beams requires carefully balancing a plethora of physical effects and is challenging—both conceptually and in experiments. We use Bayesian optimization of key laser and plasma parameters to flatten the longitudinal phase space of an ionization-injected electron bunch via optimal beam loading.

Results

Conclusion