Experimental observation of superradiance in millimeter-wave band

The first experimental results of the observation of superradiance from a single subnanosecond electron bunch are presented. Superradiance was associated with different varieties of stimulated emission (bremstruhlung, cyclotron, Cherenkov, etc). Unique megawatt power level microwave pulses of short duration (0.3-0.5 ns) have been obtained

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

Superradiance of intense electron bunches

One of the attractive methods of generating an ultrashort electromagnetic pulse is based on stimulated emission from intense extended electron bunches. Radiation from such bunches may be considered as a classical analogue well known in quantum electronics as Dike's superradiance effect (SR). Superradiance of classical electrons may be associated with different mechanisms of stimulated emission (cyclotron, Cherenkov, bremsstrahlung etc). Different types of SR were recently observed experimentally at millimeter and centimeter wavelength bands. Progress in this research has enabled a new type of millimeter band generator to be created, which is capable of generating unique short (200-300 ps) electromagnetic pulses at super high peak powers exceeding 1 GW

Features of Electron Runaway in a Gas Diode with a Blade Cathode

Conditions for electron runaway in a gas diode with a blade cathode providing a strongly inhomogeneous distribution of the electric field in the interelectrode gap have been studied theoretically. It has been demonstrated that the character of electron runaway differs qualitatively for cathodes with a different rounding radius of the edges. In the case of a relatively large edge radius (tens of microns or more), the conditions for the transition of electrons to the runaway mode are local in nature: they are determined by the field distribution in the immediate vicinity of the cathode where the electrons originate from. Here, the relative contribution of the braking force acting on electrons in a dense gas reaches a maximum. This behavior is generally similar to the behavior of electrons in a uniform field. For a cathode with a highly sharpened edge, the relative contribution of the braking force is maximum in the near-anode region. As a consequence, the runaway condition acquires a nonlocal character: it is determined by the electron dynamics in the entire interelectrode gap

Features of Electron Runaway in a Gas Diode with a Blade Cathode

Conditions for electron runaway in a gas diode with a blade cathode providing a strongly inhomogeneous distribution of the electric field in the interelectrode gap have been studied theoretically. It has been demonstrated that the character of electron runaway differs qualitatively for cathodes with a different rounding radius of the edges. In the case of a relatively large edge radius (tens of microns or more), the conditions for the transition of electrons to the runaway mode are local in nature: they are determined by the field distribution in the immediate vicinity of the cathode where the electrons originate from. Here, the relative contribution of the braking force acting on electrons in a dense gas reaches a maximum. This behavior is generally similar to the behavior of electrons in a uniform field. For a cathode with a highly sharpened edge, the relative contribution of the braking force is maximum in the near-anode region. As a consequence, the runaway condition acquires a nonlocal character: it is determined by the electron dynamics in the entire interelectrode gap

Generation of subnanosecond superradiance pulses in the short-wavelength part of the millimeter range

Results of a simulation are presented and experimental observations of the generation of superradiance pulses in the 4 and 2 mm wavelength ranges as a result of the rectilinear motion of a subpicosecond high-current electron beam through a periodic retarding system are described. In the 4 mm range the microwave pulse power reached 10-15 MW with a duration of 150 ps