Impact of Spent Electrons on BWO Operation

As a result of their interaction with an operating wave in a backward-wave oscillator (BWO), electrons give up their energy to the electromagnetic field and acquire a large energy spread. The energy spread decreases the space-charge-limiting current, which can result in the formation of a virtual cathode (VC) for low-energy electrons in the output channel. We analyze the influence of electrons reflected from the VC on BWO operation, which manifests as a decrease in the generated power and in the appearance of modulated power. In the region of cyclotron absorption, the reflected electrons cause high-frequency generation with a high noise level.