Coherent Summation of Emission From Relativistic Cherenkov Sources as a Way of Production of Extremely High-Intensity Microwave Pulses

Abstract

For relativistic Cherenkov devices we investigate the process of high-power microwave (HPM) pulse generation with its phase correlating to the sharp edge of an e-beam current pulse. Our theoretical consideration is referred to quasistationary and superradiative (SR) generation regimes when spontaneous emission of the e-beam edge serves as the seed for the development of further coherent oscillations. Phase correlation of the excited microwave pulses with the characteristics of the current pulse front and/or an initial external electromagnetic pulse provided additional confirmation of particle-in-cell (PIC) simulations. Pulse-to-pulse stability of the radiation phase within several percent of the oscillation period makes it possible to arrange multi-channel schemes producing mutually coherent microwave pulses. In the experiments that have been carried out, the cathodes of independent generators were powered by identical accelerating pulses from strictly synchronized voltage modulators, or by splitting the pulse from a single powerful modulator. For the 2-ns regime with the power of each Ka-band backward wave oscillator (BWO) about 100 MW, we demonstrate quadratic growth of the power density in the interference maximum of the directional diagram. In a short pulse SR regime, with the peak power of 600 MW in a single channel, for a four-channel 2-D array we attained a sixteen-fold radiation intensity gain.

Relativistic microwave oscillators with high power flux in a free space and interaction zone

“…This was proven (see, e.g., Ref. [5] and citation therein) when in-phase operation of multi-channel BWOs (X-band and Ka-band) was provided by a split of a single voltage pulse. Figure 3 (a) shows the radiation pattern of 2-D (2x2) array of 38-GHz, 0.6-GW SR BWOs.…”

“…[1][2][3][4][5][6] and citation therein). For generation of HPM pulses with duration of units of nanosecond and less influence of microwave breakdowns of electrodynamics systems, expansion of cathode and collector plasmas, and electron beam structure distortions becomes insignificant.…”

Wave Beams of Short Radio Pulses Generated by Gigawatt Microwave Sources

“…A rising interest to the generation of short pulses is observed lately [1][2][3]. In relativistic backward wave oscillators (BWO) operating in superradiance regime the peak power of output radiation may exceed the power of electron beam [1,2].…”

Directivity patterns features of antenna systems in regimes of ultra-short microwave pulses radiation

“…Recent advances in synchronisation of high power generators [1,2] open new opportunities in development of their arrays with record radiation pulse power. However, the extreme power of such generators (of the order of 10 8 -10 9 W) requires development of specific multichannel antenna systems.…”

“…Dimensions of the output window of each generator cannot be less than a several wavelengths because of microwave breakdown on smaller apertures. It means that the distance between channels in the arrays of high-power generators are much greater than wavelength and side lobe levels in array directivity patters are high (see [1,2] for instance). Another important parameter characterizing high-power generators is short or ultra-short pulse duration.…”