Energy limitation of laser-plasma electron accelerators

TL;DR

This paper investigates the fundamental dephasing limit in laser wakefield accelerators through precise measurements using shock-front injection, revealing how electron energy evolves with plasma density and laser pulse duration.

Contribution

It provides high-precision measurements of dephasing effects in laser-plasma accelerators and demonstrates a simple model describing the density-dependent electron energy evolution.

Findings

Dephasing length ranges from 65-300 micrometers.

Electron energies peak between 6-20 MeV.

Dephasing effects are well described by a simple model.

Abstract

We report on systematic and high-precision measurements of dephasing, an effect that fundamentally limits the performance of laser wakefield accelerators. Utilizing shock-front injection, a technique providing stable, tunable and high-quality electron bunches, acceleration and deceleration of few-MeV quasi-monoenergetic beams were measured with sub-5-fs and 8-fs laser pulses. Typical density dependent electron energy evolution with 65-300 micrometers dephasing length and 6-20 MeV peak energy was observed and is well described with a simple model.