Optical control of transverse motion of ionization injected electrons in a laser plasma accelerator

Jie Feng,Dazhang Li,Feng Liu,Jinguang Wang,Junhao Tan,Yifei Li,Xiaotao Geng,Changqing Zhu,Liming Chen

doi:10.1017/hpl.2020.51

Abstract

Abstract We demonstrate an all-optical method for controlling the transverse motion of an ionization injected electron beam in a laser plasma accelerator by using the transversely asymmetrical plasma wakefield. The laser focus shape can control the distribution of a transversal wakefield. When the laser focus shape is changed from circular to slanted elliptical in the experiment, the electron beam profiles change from an ellipse to three typical shapes. The three-dimensional particle-in-cell simulation result agrees well with the experiment, and it shows that the trajectories of these accelerated electrons change from undulating to helical. Such an all-optical method could be useful for convenient control of the transverse motion of an electron beam, which results in synchrotron radiation from orbit angular momentum.

Highlights

The concept of laser plasma wakefield accelerators (LWFAs) was first proposed by Tajima and Dawson[1]
We propose a simple all-optical method to control the transverse motion of the ionization injected electron beam by changing the evolution of the plasma wakefield transversal distribution
The electron beams emitted from the plasma channel were detected by a DRZ fluorescent screen coupled with a 16bit electron-multiplying charge-coupled device (CCD) (EM-CCD)

Summary

Introduction

The concept of laser plasma wakefield accelerators (LWFAs) was first proposed by Tajima and Dawson[1]. The ponderomotive force of these laser pulses propagating in an underdense plasma pushes the background electrons away from the high-intensity regions and drives a relativistic plasma wave. The wave consists of a string of ion cavities ( referred to as ‘bubbles’), and the electrons trapped inside can be accelerated by the electrostatic field set up by the separation of electrons and ions. These accelerated electrons will oscillate√in the plasma ωp/ 2γ and emit wakefield with betatron synchrotron radiation[7]

Methods

Discussion

Conclusion