Mechanism of spontaneous pulse shortening and a method to lengthen microwave pulse in a gigawatt relativistic BWO

Summary form only given. Spontaneous pulse shortening occurring in the relativistic BWO at a gigawatt power level is studied by experiment and theory. In the first experiments with a 3-GW relativistic BWO, spontaneous microwave pulse width limitation a 6 ns was observed. It is now experimentally demonstrated that this phenomenon is accompanied by formation of an explosive-emission plasma at the surface of a corrugated slow wave structure and by the appearance of intense electron flows between the SWS ripples. The termination of microwave emission is explained in terms of increase of the BWO starting current due to partial absorption of the operating electromagnetic wave by electrons emitted from the plasma, while the intensity of the absorption radically increases owing to the presence of positive ions emitted from the plasma. To improve the electric strength of the BWO electrodynamic system, treatment of its surface with low-energy, high-current electron beam (LEHCEB) is proposed. Effectively smoothing the metal surface and removing dielectric inclusions from the surface layer, such treatment allows suppression of the explosive emission.