Generation of a periodic sequence of ultrashort electromagnetic pulses in a scheme with two parallel radiating and absorbing electron beams

We demonstrate the possibility of generating periodical trains of ultrashort microwave pulses based on the effect of passive mode-locking in a scheme with two parallel coaxial electron beams formed by a single cathode and transported in a single vacuum volume. The external tubular beam provides amplification of radiation during rectilinear motion along a periodic slow-wave structure, while the internal paraxial beam provides nonlinear cyclotron absorption.