Comparison of coherent Smith-Purcell radiation generated by 6.1 MeV electron beam in metal and dielectric lamellar gratings

TL;DR

This study compares the coherent Smith-Purcell radiation from metal and dielectric lamellar gratings generated by a 6.1 MeV electron beam, revealing differences in intensity and spectral structure that could aid development of new THz sources.

Contribution

It introduces a simple theoretical model applicable to both grating types and provides experimental validation of their differing radiation characteristics.

Findings

Dielectric gratings produce more intense radiation below the coherent threshold.

Radiation from dielectric gratings exhibits a non-monotonic peak structure.

Differences in radiation characteristics can inform development of compact THz sources.

Abstract

Coherent Smith-Purcell radiation generated by bunched electron beam in the lamellar metal and dielectric gratings in the millimeter wavelength range was compared theoretically and experimentally. For theoretical estimation a simple model suitable for both dielectric and metal gratings was developed. Experimental comparison was carried out using extracted bunched 6.1 MeV electron beam of the microtron at Nuclear Physics Institute (Tomsk Polytechnic University). Both theoretical estimations and experimental data showed the difference of the radiation characteristics from the lamellar metal and dielectric gratings. The radiation from the dielectric grating had peak structure not monotonic one and was more intense comparing with metal grating radiation in the wavelength less than coherent threshold. These differences may be useful for research and development of new compact monochromatic radiation sources in sub-THz and THz region.