Tunable THz radiation source from dielectric loaded waveguide excited by nonrelativistic electron bunch trains

Weiwei Li,Zhigang He,Weihao Liu,Yalin Lu,Lin Wang,Ruixuan Huang,Qika Jia

doi:10.1103/physrevaccelbeams.19.104701

Abstract

We propose a novel scheme to generate a tunable narrow-band THz radiation. In this scheme, a train of laser pulses with THz repetition rate is used to drive a photocathode direct current (DC) gun, leading to the emission of a train of electron bunches. The electron bunch train is subsequently accelerated by the gun field and applied to selectively excite one of the modes in the dielectric loaded waveguide (DLW) structure, which is located downstream the DC gun. Thanks to the tunability of the repetition rate of laser pulses and the gun voltage, a tunable narrow-band THz radiation source can be obtained. This proposed source has the advantages of compactness, robustness and relatively high power.

Highlights

Terahertz (THz) radiation, which lies in the frequency gap between the infrared and microwaves, typically referred to as the frequencies from 100 GHz to 30 THz, is finding use in an increasingly wide variety of applications [1,2]
Broad-band THz sources are often based on coherent synchrotron radiation (CSR) [4,5,6] and coherent transition radiation (CTR) [7,8,9,10] excited by ultrashort electron bunches
Narrow-band THz radiation can be obtained by using FEL technology [11,12,13,14,15], dielectric loaded waveguide (DLW) [16,17] and other slow wave structures [18,19] as emitter, and train of electron bunches as driving beam [20,21,22,23,24,25,26]

Summary

INTRODUCTION

Terahertz (THz) radiation, which lies in the frequency gap between the infrared and microwaves, typically referred to as the frequencies from 100 GHz to 30 THz, is finding use in an increasingly wide variety of applications [1,2]. Narrow-band THz radiation can be obtained by using FEL technology [11,12,13,14,15], dielectric loaded waveguide (DLW) [16,17] and other slow wave structures [18,19] as emitter, and train of electron bunches as driving beam [20,21,22,23,24,25,26] These kinds of sources can generate the radiation of above megawatt peak power with a spectrum covering the whole terahertz band, yet their practical applications are limited by the large equipment, enormous cost and complicated peripherals, such as microwave power source, radiation shielding, etc. The radiation frequency can be tuned from 0.1 THz to above 1.0 THz, and the peak power of the radiation pulse can be up to the order of Watt, which is much higher than that of other THz sources based on the nonrelativistic electron beam

PRINCIPLE OF THE PROPOSED SCHEME

GENERATION OF ELECTRON BUNCH TRAIN

SIMULATION RESULTS OF THE RADIATION

SUMMARY AND DISCUSSION