Spectrum of coherent transition radiation generated by a modulated electron beam

The spectrum of coherent transition radiation has been recorded with the use of a Martin–Puplett interferometer. It has been shown that the spectrum includes monochromatic lines that are caused by the modulation of an electron beam with the frequency of an accelerating radio-frequency field $\nu_{\text{RF}}$ and correspond to resonances at $\nu_k=k\cdot \nu_{\text{RF}}$, $k\leq 10$. To determine the length of an electron bunch from the measurement of the spectrum from a single bunch, it is necessary to use a spectrometer with the resolution $\Delta\nu_{\text{sp}}>\nu_{\text{RF}}$.