3-D particle-in-cell simulations for quasi-phase matched direct laser electron acceleration in density-modulated plasma waveguides

TL;DR

This paper presents 3-D particle-in-cell simulations demonstrating how density-modulated plasma waveguides can facilitate quasi-phase matched direct laser electron acceleration using moderate laser power, optimizing electron bunch properties and energy gain.

Contribution

The study introduces a comprehensive 3-D PIC simulation model for DLA in plasma waveguides, analyzing injection timing, bunch size, and waveguide length effects on acceleration efficiency and electron beam quality.

Findings

Injection delay controls electron bunch transverse properties and energy gain.

Longer injected bunches improve collimation and reduce emittance.

Moderate laser power and extended waveguides enhance energy gain.

Abstract

Quasi-phase matched direct laser acceleration (DLA) of electrons can be realized with guided, radially polarized laser pulses in density-modulated plasma waveguides. A 3-D particle-in-cell model has been developed to describe the interactions among the laser field, injected electrons, and the background plasma in the DLA process. Simulations have been conducted to study the scheme in which seed electron bunches with moderate energies are injected into a plasma waveguide and the DLA is performed by use of relatively low-power (0.5-2 TW) laser pulses. Selected bunch injection delays with respect to the laser pulse, bunch lengths, and bunch transverse sizes have been studied in a series of simulations of DLA in a plasma waveguide. The results show that the injection delay is important for controlling the final transverse properties of short electron bunches, but it also affects the final energy gain. With a long injected bunch length, the enhanced ion-focusing force helps to collimate the electrons and a relatively small final emittance can be obtained. DLA efficiency is reduced when a bunch with a greater transverse size is injected; in addition, micro-bunching is clearly observed due to the focusing and defocusing of electrons by the radially directed Lorentz force. DLA should be performed with a moderate laser power to maintain favorable bunch transverse properties, while the waveguide length can be extended to obtain a higher maximum energy gain, with the commensurate increase of laser pulse duration and energy.