Interactions of electron beams with electromagnetic waves in Cherenkov devices

A simple unified theory is developed to describe the interactions between electron beams and electromagnetic waves in Cherenkov devices. The simple expression is developed for the analysis of the gain of Cherenkov devices composed of periodic metal slow-wave structures (SWS). In principle, the linear analysis can be applied to describe all kinds of instabilities in various Cherenkov devices with appropriate extension of the coupling coefficient. The results for Cherenkov devices with two typical SWSs profiles are presented.