Recent progress in understanding the physics of plasma-filled, high-power microwave sources

The use of plasmas for generating high-power microwaves is studied for more than 50 years. During the 1990's Plasma-Assisted Slow-wave Oscillators (PASOTRONs) were invented and actively developed at Hughes Research Lab (HRL). These devices have a number of unique and attractive features. However, the experiments at HRL showed that to explore these features a better understanding of the physics is necessary. The present paper is focused on the recent studies of various physical issues, which are important for the pasotron operation. This theoretical and experimental activity resulted in more than doubling the pasotron efficiency (from about 20% to more than 50%) in the experiments carried out at the University of Maryland.