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Description
Narrowband Cherenkov radiation in the millimeter-wave and sub-terahertz frequency ranges has attracted considerable attention as a compact and tunable source of coherent electromagnetic radiation. In particular, radiation in the 30–50 GHz range can be generated when relativistic electron beams propagate through dielectric structures under conditions satisfying the Cherenkov criterion. Compared with broadband emission mechanisms, narrowband Cherenkov sources provide enhanced spectral selectivity, making them attractive for high-resolution spectroscopy, imaging, diagnostics, and accelerator-based applications.
In this work, experimental studies were carried out to investigate the spectral properties of coherent Cherenkov radiation from a cylindrical Teflon radiator produced by two subsequent electron bunches at the AREAL accelerator. The influence of the inter-bunch delay on the coherent radiation intensity was examined for delays ranging from 1 to 41 ps. Radiation detection was performed using a narrowband Schottky barrier diode detector coupled to a waveguide-fed pyramidal horn antenna operating in the 33–50 GHz frequency range. The spectral characteristics of the emitted radiation were analysed using a measurement setup incorporating a Martin–Puplett interferometer. The obtained experimental results show good agreement with theoretical expectations.