Speaker
Description
We report the results of experimental and theoretical studies of coherent terahertz radiation generated by a short electron bunch from a metasurface. The metasurface is an array of sub-wavelength copper spherical-like elements placed on a monocrystalline sapphire substrate. The target has two periodicities, along and perpendicular to the electrons trajectory. Experiment was carried out using 8 MeV electron beam of KEK LUCX facility. The target was installed into 5D in-vaccuum manipulator so it could be positioned and inclined with respect to the electron beam. Because of that, several types of radiation and its properties were confirmed: Smith-Purcell radiation, Transition radiation, Grating transition radiation, Cherenkov radiation inside a substrate. The main characteristics of the radiation like spectrum, spectral-angular distribution, characteristic angle of emitted radiation, and dispersion relation were calculated. The experimental and theoretical results are compared, and good agreement is demonstrated.