Colliding ionization injection in a beam driven plasma accelerator

TL;DR

This paper investigates a novel ionization injection method in beam-driven plasma accelerators using counter propagating lasers, achieving ultra-low energy spread and high brightness electron bunches through simulation.

Contribution

It introduces a new ionization injection technique with adjustable parameters, resulting in high-quality electron bunches with extremely low energy spread and high brightness.

Findings

Electron bunches with slice energy spread of 15 keV achieved.

Injection distance can be controlled by laser and beam timing.

High brightness electron bunches suitable for light sources obtained.

Abstract

The proposal of generating high quality electron bunches via ionization injection triggered by an counter propagating laser pulse inside a beam driven plasma wake is examined via two-dimensional particle-in-cell simulations. It is shown that electron bunches obtained using this technique can have extremely small slice energy spread, because each slice is mainly composed of electrons ionized at the same time. Another remarkable advantage is that the injection distance is changeable. A bunch with normalized emittance of 3.3 nm, slice energy spread of 15 keV and brightness of $7.2\times 10^{18}$ A m$^{-2}$ rad$^{-2}$ is obtained with an optimal injection length which is achieved by adjusting the launch time of the drive beam or by changing the laser focal position. This makes the scheme a promising approach to generate high quality electron bunches for the fifth generation light source.