Strong electron density modulation with a low-power THz source for generating THz superradiant undulator radiation

Gang Zhao,Sheng Zhao,Kexin Liu,Senlin Huang

doi:10.1103/physrevaccelbeams.22.060701

Abstract

We propose a scheme to modulate a low-emittance electron beam at THz frequency using a low-power optical THz source (seed). In this scheme, a matching section introduces tunable angular dispersion and focusing to the electrons. It helps to slice the electrons into ``energy layers'' and largely cancels out the impact of uncorrelated energy spread on electron modulation. Analytical and numerical studies have been carried out to demonstrate the proposed scheme. It is found that a strong electron density modulation (bunching) over the frequency range from 1 to 6 THz can be achieved when the peak power of THz seed is no more than 1 kW. The bunched beam can be used to generate superradiant undulator radiation with the peak power of 10s MW.

Highlights

Terahertz (THz) radiation has many scientific and technological applications, such as molecular spectroscopy, remote sensing, security screening, medical, and biological imaging [1,2,3]
Among the numerous THz radiation sources, the accelerator-based THz sources are relatively complex but can generate high peak power beyond megawatt (MW) level [4,5], which is considerably attractive for its unique application in driving new nonlinear phenomena of materials [6]
There has been great interest in generating intense narrowband THz radiation from electron beams bunched at picosecond and sub-ps scale [7,8,9,10,11]

Summary

INTRODUCTION

Terahertz (THz) radiation has many scientific and technological applications, such as molecular spectroscopy, remote sensing, security screening, medical, and biological imaging [1,2,3]. The other is based on energy spread modulation of electron temporal slices [9], which uses a laser pulse with periodic intensity Both schemes are supposed to generate density modulation at THz frequency. Inspired by a recent technique proposed to introduce strong microbunching into the storage ring beam for generating coherent EUV and x-ray radiation [24], we propose a scheme to produce strong electron density modulation at THz frequency using an external THz source directly. In this scheme, the electron modulator comprises a matching section, an energy modulator resonant at THz frequency, and a dispersion section.

THEORETICAL BASIS

THE MODULATION SCHEME

SIMULATION STUDY

THZ SUPERRADIANT UNDULATOR RADIATION

Findings

SUMMARY