Bulletin of the Russian Academy of Sciences: Physics最新文献

The so-called method of moments is used to obtain a system of equations for the parameters of a pulse propagating in a multicomponent dispersion medium. The effect the widths of the components’ resonance lines have on the stability of a signal is investigated according to Lyapunov.

Dynamics of the fusion of two droplets of the same fluid is investigated. Numerical modeling of a two-phase gas–liquid system reveals oscillating changes in the shape of the droplets over time for different properties of the fluids. A procedure is proposed for estimating the end time of the oscillatory mode of droplet coalescence.

The concept of a distributed network of ultra-wideband multi-position radars is presented. Numerical modeling is used to detect, resolve, and precisely determine the coordinates of many closely packed targets using a single multi-position radar (carrier frequency 19 GHz, bandwidth 6 GHz). The error of determination is no more than 2 cm for both coordinates in a two-dimensional representation. The characteristics of a microwave photonics system on whose basis such a locator can be obtained are studied numerically.

The authors consider the diffraction transformation of the structure of fractal wave beams that have a periodic phase distribution and a constant amplitude in the initial plane. It is shown that the depth of phase modulation strongly affects the periodically reproducing amplitude-phase profile of the beam.

A W-band traveling wave tube with delayed feedback is studied theoretically and experimentally. Periodic pulse sequences with peak powers many times higher than the average output radiation power and typical durations of 400–500 ps were experimentally recorded.

Dynamics of the characteristic spectral parameter of a laser diode are tested by measuring and processing the emission spectra at different operating points of a high-power KLM-H980-200 laser, manufactured in a single technological cycle. The parameter for predicting the normal period of operation of the device is calculated. Physical concepts of the spectra of high-power laser diodes are discussed.

An analysis is performed of fluctuations in the radiation power of laser diodes used in analog fiber-optic communication lines. The minimum values of fluctuations in the radiation power of high-power laser diodes are estimated, based on models describing the processes in laser diodes,

Surface capillary-gravitational periodic flows are considered in a two-dimensional formulation. Complete solutions are obtained that contain waves and a fine structure of flows (ligaments in a viscous uniformly stratified incompressible fluid in the Boussinesq approximation). Dispersion relations are considered for all flow components. Expressions are obtained for the phase and group velocities of waves and analogs of them for ligaments in variables convenient for experimental verification. Characteristics obtained using different models of the environment are compared for the first time. All expressions converge uniformly to known ratios upon limit transitions.

Experimental computations are used to study the spatial-temporal structure of the radiation field of a charged particle moving in the accelerating gap of an electron gun (a diode gap). It is shown that the radiation field is in this case a unipolar electromagnetic pulse. The dependence of the shape of the emitted pulse on the rate of particle acceleration is analyzed.

A solution to the traveling salesman problem was experimentally and theoretically investigated using a stochastic magnetic tunnel junction emulator. The relationship between theoretical and experimental results was analyzed using the Ising model. A series of experiments were conducted to determine the system parameters at which the solution to the problem was most likely. General dependences of the reliability of the obtained solution on the hyperparameters were demonstrated.