Summation of emission from superradiant sources as a way to obtain extreme power density microwaves

A theoretical model that covers both spontaneous and stimulated Cherenkov emission from an extended electron bunch has been developed. The initiation is described of the generation of superradiant pulses [1-3] by emission from the leading edge of the electron bunch. In combination with the proven experimentally picosecond stability of explosive emission from a cold cathode [4], it provides the possibility for strong correlation of phase of the SR pulses with respect to the leading edge of the electron pulse [5]

Generation, amplification, and nonlinear self-compression of powerful superradiance pulses

Superradiance (SR) of electron bunches can be considered an effective method of production of ultrashort electromagnetic pulses. Different types of SR associated with different mechanisms (cyclotron, Cherenkov, and bremsstrahlung) of stimulated emission are observed experimentally in the millimeter and centimeter wavelength bands. Progress in this research has enabled a new type of generator to be created capable of generating unique short (under 200-300 ps) electromagnetic pulses at super high peak powers exceeding 1 GW in the millimeter and 3 GW in the centimeter waveband. Some new methods for further increasing of the SR pulse peak power along with the promotion of such sources to higher frequency bands are discussed. These new methods include phase synchronization of several SR pulse generators, the amplification of an SR pulse during its propagation along a quasi-stationary electron beam and nonlinear compression in the process of induced self-transparency

Estimation of the cross-wind speed from turbulent fluctuations of the image of a diffuse target illuminated by a laser beam

The article presents an optical method for assessing the transverse wind, based on the analysis of turbulent distortions of the image of a diffuse target illuminated by a laser beam. The proposed correlation algorithm for processing video images allows one to assess in real time the crosswind speed using one receiving lens when the target is illuminated in the visible or infrared range. An experimental check of the method on the atmospheric path has been carried out. The optical estimates of the integral wind are compared with the data of independent local measurements of six ultrasonic anemometers located along the sensing path