A generalized linear theory of the discrete electron-wave interaction in slow-wave structures

A linear theory of the discrete interaction of electron flows and electromagnetic waves in slow-wave structures (SWSs) is developed. The theory is based on the finite-difference equations of SWS excitation. The local coupling impedance entering these equations characterizes the field intensity excited by the electron flow in interaction gaps and has a finite value at SWS cutoff frequencies. The theory uniformly describes the electron-wave interaction in SWS passbands and stopbands without using equivalent circuits, a circumstance that allows considering the processes in the vicinity of cutoff frequencies and switching from the Cerenkov mechanism of interaction in a traveling-wave tube to the klystron mechanism when passing to SWS stopbands. The features of the equations of the discrete electron-wave interaction in pseudoperiodic SWSs are analyzed.