Cerenkov radiation from periodic electron bunches

Cerenkov radiation is calculated for electron beams which exceed the velocity of radiation in a nondispersive dielectric medium. The electron beam is assumed to be bunched as emitted from a traveling-wave accelerator, and the emission region is assumed to be finite. Predictions include (a) emission at harmonics of the bunch rate, (b) coherence of radiation at low frequencies, (c) smearing of the emission angle for finite emission regions, and (d) explicit evaluation of the power spectrum in terms of bunch dimensions. The results apply to microwave emission from fast electrons in air or other dielectrics