Effects of collector plasma in the relativistic backward wave oscillator.

The effects of a collector plasma in a relativistic backward wave oscillator are investigated using a numerical simulation. Analyzing mainly the diffusion process, the results show a fast plasma diffusion occurring as one of the most important reasons for pulse shortening. In this process, the fast plasma affects the modulation of the intense relativistic electron beams, leads to drifting of the microwave frequency, absorbs gigawatts of microwave power, and finally causes pulse shortening. Here, the mechanism underpinning fast diffusion is mainly attributed to the standing wave pattern of the microwave field in the interaction region and the space charge effect. This paper reveals the change in the system after pulse shortening caused by fast diffusion and suggests a measure to control this process by restraining the collector plasma. [ABSTRACT FROM AUTHOR]