Generation of Doublets of High-Power Microwave Pulses in a Backward-Wave Oscillator by Modulating the Electron Beam Current

In a relativistic Ka-band backward-wave oscillator (BWO), the generation of doublets of superradiance (SR) pulses with multimegawatt power was achieved due to deep modulation of the current of an explosive-emission electron beam. A SR pulse interacting with the counter-propagating beam generates a strong electric field in the radial gap positioned in the region of the cylindrical insert incorporated in the BWO anode assembly instead of a commonly used resonant reflector. Here the beam is repetitively dumped onto the wall of the insert, so the SR generation fails and then the process repeats. Since the electrons reach their maximum energies within the leading edge of the subsequent segment of the total current pulse, the excitation of the next SR pulse is not significantly affected by residual slow electrons from the previous generation cycle. As a result, the time interval between measured successive SR pulses nearly matches the value of ≈1 ns obtained from numerical simulation, and their amplitudes are almost the same.