Microwave pulse shortening in plasma relativistic high-current microwave electronics

We describe mechanisms of microwave pulse shortening in radiation sources with the power of about 108 W based on interaction between relativistic electron beams of nanosecond duration and preformed plasma. The shortening is mainly due to the electron return flow through the plasma, which leads to a multiple decrease in the linear gain of the microwave by the relativistic electron beam and in the reflection coefficient of the plasma wave that provides the generator feedback. The ways to eliminate the effect of microwave pulse shortening are proposed. © 2017, Allerton Press, Inc.