Advances in plasma-filled, relativistic, slow wave microwave sources

Summary form only given. Significant improvements in the performance of microwave sources, both nonrelativistic and relativistic, have been achieved in recent years by introducing a controlled amount of background plasma. Recent advances in plasma-filled relativistic devices-both experimental and theoretical-are reviewed. In particular, plasma filling has been credited with increasing the electron beam current and frequency tunability (/spl sim/300%). The formation of hybrid waves in plasma-filled corrugated slow wave structures and the role of these modes in improving the beam/wave coupling will also be discussed We review those issues as well as recent experimental results of plasma-loaded backward wave oscillators (BWO) operating over wide range of beam currents (0.8-4 kA) and plasma densities (10/sup 10/-10/sup 13/ cm/sup -3/).