Generation of electromagnetic fields of extremely high intensity by coherent summation of Cherenkov superradiance pulses

We demonstrate both theoretically and experimentally the possibility of correlating the phase of a Cherenkov superradiance (SR) pulse to the sharp edge of a current pulse, when spontaneous emission of the electron bunch edge serves as the seed for SR processes. By division of the driving voltage pulse across several parallel channels equipped with independent cathodes we can synchronize several SR sources to arrange a two-dimensional array. In the experiments carried out, coherent summation of radiation from four independent 8-mm wavelength band SR generators with peak power 600 MW results in the interference maximum of the directional diagram with an intensity that is equivalent to radiation from a single source with a power of 10 GW

Coherent summation of emission from relativistic Cherenkov sources as a way of production of extremely high-intensity microwave pulses

For relativistic Cherenkov devices, we investigate the process of high-power microwave pulse generation with its phase correlating to the sharp edge of an e-beam current pulse. Our theoretical consideration is referred to quasi-stationary 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 has been additionally confirmed by particle-in-cell simulations. Pulse-to-pulse stability of the radiation phase within several percents of the oscillation period makes it possible to arrange multichannel 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 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 16-fold radiation intensity gain

Cerenkov superradiance from a subnanosecond electron bunch in a sectional decelerating system

Induced coherent radiation (superradiance) from a subnanosecond electron bunch in a combined decelerating system has been investigated experimentally. In a first section formed by a periodically modulated waveguide, the density of the bunch is modulated and it then radiates in a second section formed by a waveguide partially filled with a dielectric. At an electron energy of 250 keV and a peak current of 800 A, millimeter radiation pulses with powers up to 2 MW and lengths up to 800 ps were obtained

A new source of ultra-short microwave pulses based on the effect of superradiation of subnanosecond electron clusters

Describes a new source of ultra-short microwave pulses based on the effect of superradiation of subnanosecond electron clusters

INVESTIGATION OF RADIAL AIR BREAKDOWN BY TRAVELING TEM-WAVE INITIATED BY RUNAWAY ELECTRONS

Investigations of the air breakdown in the field of traveling TEM-wave have been per-formed. Also researches of the breakdown were carried out both at various amplitudes and at different durations of high voltage pulse

Experimental observation of cyclotron superradiance under group synchronism conditions

Intense microwave pulses (several hundreds of kilowatts) of ultrashort duration (less than 0.5 ns) were obtained from an ensemble of electrons rotating in a uniform magnetic field. The comparison with theoretical simulations proves that this emission can be interpreted as cyclotron superradiance. The maximum radiation power was achieved under group synchronism conditions, when the electron bunch translational velocity coincides with the group velocity of the wave propagating in the waveguide