Control of the Operation Mode of a Relativistic Ka-Band Backward-Wave Oscillator

Variations in the transient time and in the microwave pulse duration and peak power have been demonstrated for a relativistic subgigawatt Ka -band backward-wave oscillator (BWO) with the slow-wave structure geometry, the accelerating voltage, and the electron beam current remained unchanged. This was done taking into account that the BWO operation mode depends on the starting-current-to-beam-current ratio. Efficient variation of the starting current was attained by changing the beam path in view of a significant difference between the times of the guide pulsed magnetic field diffusion into the electron injection region and beam-wave interaction space.