Generating high quality ultra-relativistic electron beams using an evolving electron beam driver

TL;DR

This paper introduces a novel method for generating high-quality ultra-relativistic electron beams using controlled injection in the nonlinear blowout regime, demonstrated through particle-in-cell simulations with promising brightness and emittance results.

Contribution

The paper proposes a new controllable injection technique in the nonlinear blowout regime driven by electron beams, utilizing varying drive beam spot size and CS parameters, validated by theory and simulations.

Findings

Achieved peak normalized brightness > 10^{20} A/m^2/rad^2

Projected energy spread less than 1% in the injected beam

Normalized slice emittance as low as 10 nm

Abstract

A new method of controllable injection to generate high quality electron bunches in the nonlinear blowout regime driven by electron beams is proposed and demonstrated using particle-in-cell simulations. Injection is facilitated by decreasing the wake phase velocity through varying the spot size of the drive beam and can be tuned through the Courant-Snyder (CS) parameters. Two regimes are examined. In the first, the spot size is focused according to the vacuum CS beta function, while in the second, it is focused by the plasma ion column. The effects of the driver intensity and vacuum CS parameters on the wake velocity and injected beam parameters are examined via theory and simulations. For plasma densities of $\sim 10^{19} ~\text{cm}^{-3}$, particle-in-cell (PIC) simulations demonstrate that peak normalized brightnesses $\gtrsim 10^{20}~\text{A}/\text{m}^2/\text{rad}^2$ can be obtained with projected energy spreads of $\lesssim 1\%$ within the middle section of the injected beam, and with normalized slice emittances as low as $\sim 10 ~\text{nm}$.