Plasma electronics. Theoretical and experimental investigations of plasma nonlinearity in the traveling-wave tube oscillators

Abstract

Many years of plasma electronics development has led to powerful microwave devices creation. Due to use of plasma-filled electromagnetic structures these devices exhibit significant increase of efficiency, power and radiation bandwidth. Plasma-filled traveling-wave oscillators have been developed and studied. Special investigations of low frequency plasma oscillations, which appear in the powerful plasma-filled microwave devices, have been carried out. Such oscillations are one of the possible reasons for microwave generation pulse shortening. The usual premise of many investigations of beam-plasma instability is the assumption of independence of plasma parameters from microwave power. However various reasons for a dependence exist and the main are high frequency pressure (HFP) and high frequency discharge. Both these reasons lead to the appearance of a plasma longitudinal inhomogeneity. The resonance character of a beam-wave interaction makes it very sensitive to the inhomogeneity of the medium where the wave is propagated. Experiments are described which show that the role of HFP in increasing microwave power growth. It is confirmed by the large difference between plasma densities near the input and output ends of the system.