Relativistic Ka-band backward-wave oscillators with stable phase

Abstract

Time-domain analysis of Ka-band rf signals was applied to compare the phase stability of excitation of powerful quasi-stationary and superradiance backward-wave oscillators (BWO) driven by relativistic high-current electron beam (∼500 keV, ∼4 kA). It was revealed that if the rise rate of the voltage applied to explosive electron emission cathode approaches to 1 MV/ns, then the radiation phase is linked to the voltage front region with a maximum time derivative. Besides, at all other conditions being equal, superradiance BWO demonstrates less rf phase standard deviation from pulse to pulse, as compared to a quasi-stationary one—below one picosecond on a time scale.