Classical Field Theory of Cerenkov Radiation Devices

The usually continuous and incoherent Cerenkov radiation (CR) is converted into coherent and narrow-band radiation from within a dielectric-line cavity excited by a dc electron beam. We have studied the self-oscillating behavior of a device that operates at $\sim22$ GHz by calculating explicitly the electron self-bunching and radiation growing processes. The nonlinear gain of the device and the radiation spectrum are also calculated. The agreement to the experiments indicates that the developed formalism could be used in designing a THz source based on cavity Cerenkov radiation.