Nano-scale electron bunching in laser-triggered ionization injection in plasma accelerators

TL;DR

This paper investigates nano-scale electron bunching in laser-triggered ionization injection within plasma accelerators, revealing phase-dependent ionization effects and potential applications in high-power UV radiation generation.

Contribution

It provides a theoretical analysis and 3D simulations showing how discrete electron injection leads to nano-scale bunching constrained by 3D effects, advancing understanding of beam structuring.

Findings

Wave number of modulation limited to 2k_0 - 5k_0

Nano-scale electron bunches can be diagnosed via coherent transition radiation

Potential for high-power UV radiation generation in resonant undulators

Abstract

Ionization injection is attractive as a controllable injection scheme for generating high quality electron beams using plasma-based wakefield acceleration. Due to the phase dependent tunneling ionization rate and the trapping dynamics within a nonlinear wake, the discrete injection of electrons within the wake is nonlinearly mapped to discrete final phase space structure of the beam at the location where the electrons are trapped. This phenomenon is theoretically analyzed and examined by three-dimensional particle-in-cell simulations which show that three dimensional effects limit the wave number of the modulation to between $> 2k_0$ and about $5k_0$, where $k_0$ is the wavenumber of the injection laser. Such a nano-scale bunched beam can be diagnosed through coherent transition radiation upon its exit from the plasma and may find use in generating high-power ultraviolet radiation upon passage through a resonant undulator.