State of the Art in Pulse-Repetitive Generation of GW-Level Superradiative Pulses

The superradiative regime of relativistic BWO allows achieving not only extremely high microwave power but under some conditions also the very stable parameters (peak power, central frequency and RF phase relatively voltage rise time) from one pulse to another. The moderately dispersive spread of group velocities in the frequency band of short microwave pulse might plays the important role for the peak power hold. The results of experiments on pulse-periodic generation of X-band (9.7 GHz) short pulses are presented. Microwave pulses with peak power up to 2 GW and 0.7 ns duration were produced with the use of magnetic field in the slow wave structure as high as 2.2 T. The repetition rate was 100 p.p.s. for the batches with duration up to 2 sec. The cathode voltage was of 370 kV and beam current was 4 kA. Conditions of stable output power value were found when the root mean square deviation of detector signals was in two times less than rms of accelerating voltage pulses. Because of the rise time of cathode voltage should be optimal, the ferrite-loaded section of coaxial transmission line was used. This method of voltage pulse sharpening could provide the reduction of rise time from 2.5 to 0.6 ns at the level 300-400 kV.