ABSTRACT
The general class of O-type Cerenkov devices includes versions of the relativistic backward wave oscillator (BWO) and the traveling wave tube (TWT), higher-voltage and high-current versions of the conventional BWO and TWT. For their operation, all of these devices depend on some type of slow-wave structure (SWS), which reduces the axial phase velocity of the microwaves within the device to a speed slightly below that of the beam electrons and thus less than the speed of light. Consequently, the electrons radiate in these devices in a manner analogous to electrons emitting Cerenkov radiation when they travel through a medium at a speed greater than the local speed of light. They are called O-type devices because the electrons travel along the axial magnetic field that guides them through the device, rather than across the field as in M-type devices such as the magnetron.
