Хаос

The work studies the effects of temperature on drift velocity of the electrons in semiconductor superlattices in electric and tilted magnetic fields. It is shown that a thermal distribution of the electrons can counter­intuitively enhance the phenomena related to resonances between the Bloch and the cyclotron frequencies of electron motion in superlattices. In particular, the increase of temperature leads to more prominent resonant maxima in the dependence of drift velocity of electrons on the strength of an electric field.

A modified radio­electronic analog of the nonlinear ring cavity is realized in laboratory. The device represents a special class of oscillations or waves sources. An operation principle of the sources is based on interference amplification of feedback signal by an input signal. A laboratory experiments are performed, the likeness of their results and simulation data is shown. An intermittency, chaos, regular, static modes are detected. A thesis on controlled nonlinearity of dynamical systems is suggested.

Stochastic operation of the parallel–connected buck convertors is considered. For qualitative analysis of the system the bifurcation diagrams are plotted. Quantitative analysis of chaotic regimes was realized by computing of main and special fractal dimensions.

The attempt is undertaken to define a class of oscillations or waves sources, the operation principle of which is based on interference amplification of feedback signal by an input signal. The precedent here is the optical Ikeda’s system. The radio­electronic analog of a nonlinear ring interferometer and it modification are offered, the block diagrams and mathematical models are constructed. The computer simulation is performed. An intermittency, chaos, regular, static modes are detected.

Mathematical model of Volume Free Electron Lasers (VFEL) is described. Some aspects and origins of VFEL chaotic dynamics are examined.

We consider several electronic circuits, which are represented dynamical systems with hyperbolic chaotic attractors, such as Smale–Williams and Plykin attractors, and present results of their simulation using the software package NI Multisim 10. The approach developed is useful as an intermediate step of constructing real electronic devices with structurally stable hyperbolic chaos, which may be applicable in systems of secure communication, noise radar, for cryptographic systems, for random number generators.

The 1.5 D code program of numerical simulation of nonlinear nonstationary processes in the klystron-type devices based on the nonstationary L.A. Vainshtein’s theory of cavity excitation and the «particle-in-cell» method for modeling of the electron beam dynamics is developed. The results of numerical simulation of the basic oscillation modes of the fourcavity klystron oscillator with the external delayed feedback are presented.

A new approach is considered to design of parametric generators of chaos with hyperbolic attractors on the basis of two alternately excited subsystems, each consisting of three oscillators, one of which plays the role of the pump source. In contrast to previously proposed schemes, the angular variable undergoing a multiple increase over each characteristic period is a quantity characterizing the amplitude ratio of two oscillators, rather then the phase of successive oscillation trains.

Experimental investigations results of the ring self-oscillatory system based on a ferromagnetic film at three-wave interactions were considered. The model describing this system was constructed. The typical regimes of a generation, including generation of the chaotic microwave train were calculated with the help of the constructed model. The numerical simulations and experimental results had a good agreement.

We review the results of studies of spontaneous and stimulated emission of relativistic particles in natural and photonic crystals.We consider the diffraction of electromagnetic waves in a crystal, and the resonance and parametric (quasi-Cherenkov) X-ray radiation, the radiation in the channeling of relativistic particles in crystals, diffraction radiation in conditions of channeling, diffraction radiation of a relativistic oscillator, induced radiation in multidimensional space-periodic resonators (natural or artificial (electromagnetic, photonic) crystals).