Microwave devices designed on the basis of multipole lenses (ring electromagnetic structures using resonant sections of slow-wave structures) are analyzed. The possibility of development on the basis of these lenses of a low-noise amplifier and a microwave multiplier, which ensure long-term interaction of the electron beam and the transversely extended electromagnetic field with continuous extraction of energy, is shown.
A linear theory of the discrete interaction of electron beams and electromagnetic waves in slow-wave structures (SWS) 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 beam 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.