Plasma induced gain enhancement in backward wave oscillators using pencil beams

Summary form only given. Experiments on plasma induced performance enhancement in backward wave oscillators using pencil beams have recently been carried out. Bliokh et al. (1994) attributed the enhancement to the excitation of beam-plasma instability. If this mode is also in resonance with the desired backward wave oscillation, the beam-wave interaction is observed to be substantially enhanced. Goebel et al. (1994) observed that the background plasma neutralizes the beam DC space charge force and produces a pinching Q force which increases the beam current density and facilitates the beam transport. We have carried out computer simulations which show that the device gain can be enhanced just from the response of plasma to the backward wave oscillation without invoking the beam-plasma instability. This is because the direction of plasma response field is always in the same direction as that of the backward wave oscillation.