Cherenkov oscillator operating at the second band gap of leakage waveguide structures

Kyu-Ha Jang,Kitae Lee,Seong Hee Park,Young Uk Jeong

doi:10.1063/1.4966255

Abstract

An electromagnetic wave source operating around second band gaps of metallic grating structures is presented. The considered metallic grating structures are not perfect periodic but inhomogeneously structured within a period to have a second band gap where the wavelength is equal to the period of the structures. The radiation mechanism by an electron beam in the structures is different from the well-known Smith-Purcell radiation occurring in perfect periodic grating structures. That is, the radiating wave has a single frequency and the radiation is unidirectional. When the energy of the electron beam is synchronized at the standing wave point in the dispersion curves, strong interaction happens and coherent radiation perpendicular to the grating surface is generated with relatively lower starting oscillation current.

Highlights

In 1953, Smith and Purcell observed for the first time visible radiation over a diffraction grating in transmitting an electron beam with energy of about 300 kV.[1]
There have been several theoretical prediction and experimental studies on grating-based radiation for developing a compact coherent radiation source.[2,3,4,5,6,7,8]. Those recent researches have demonstrated that the bunching process of electron beams in an open grating structure is same as that in backward wave oscillators
Unlike typical open grating structures that are perfectly periodic, the metallic grating structures introduced in this paper could produce waves of which exciting and radiating frequency are same and the electron bunching process is developed by the standing wave not by the backward wave

Summary

Introduction

In 1953, Smith and Purcell observed for the first time visible radiation over a diffraction grating in transmitting an electron beam with energy of about 300 kV.[1]. The radiating frequencies are the high harmonics of the evanescent wave excited near the grating structure.

Results

Conclusion