Radiophysics, electronics, acoustics

Control of Collective Dynamics in a Network of Bistable Time-Delay Systems Coupled via the Mean Field

Authors: Ponomarenko V. I., Kulminskiy D. D., Borovkova E. I., Prohorov M. D.

Background and Objectives: The object of our study is a network of identical bistable time-delayed feedback systems coupled via the mean field and driven by an external harmonic signal. The mean field that provides the global coupling of time-delay systems has its own delay time, which allows one to take into account the final speed of signal propagation and processing in the medium through which the oscillators are connected.

Chimera Structures in Ensembles of Nonlocally Coupled Sprott Maps

Authors: Puzanov A. M., Anishchenko V. S., Strelkova G. I.

Background and Objectives: Recently, special attention in nonlinear dynamics and related research fields was targeted to the study of chimera states in networks of coupled oscillators. Chimeras were revealed in ensembles of nonlocally coupled identical systems which are described by both discrete- and continuous-time chaotic systems. In the paper we study numerically the dynamics of ring networks of nonlocally coupled chaotic discrete maps in order to find chimera states of different types, namely, phase and amplitude chimeras.

The Method of Visualization of Spatially Inhomogeneous Acousic Fields from Micro-Objects on the Basis of Acousto-Optic Interaction in the System with Double Fourier Transform

Authors: Nikishin E. L., Pavlova M. V., Suchilin A. V.

Background and Objectives: The method of acousto-optic visualization based on a double Fourier transform is presented. In a hybrid acousto-optic processor, the double Fourier transform is realized in the process of converting an acoustic signal from an object by an acoustic lens formed by the conjugate spherical surfaces of two crystals, and the subsequent processing of light diffracted in a photoelastic medium by an optical collecting lens.

Spiral Wave Patterns in Two-Layer 2D Lattices of Nonlocally Coupled Discrete Oscillators. Synchronization of Spiral Wave Chimeras

Authors: Bukh A. V., Strelkova G. I., Anishchenko V. S.

The paper describes the spatio-temporal dynamics of a lattice that is given by a 2D N × N network of nonlocally coupled Nekorkin maps which model neuronal activity. The network behavior is studied for periodic and no-flux boundary conditions. It is shown that for certain values of the coupling parameters, rotating spiral waves and spiral wave chimeras can be observed in the considered lattice. We analyze and compare statistical and dynamical characteristics of the local oscillators from coherence and incoherence clusters of a spiral wave chimera.

Simulation of a Sub-THz Traveling Wave Tube with Multiple Sheet Electron Beam

Authors: Ploskikh A. E., Ryskin N. M.

Background and Objectives: Many applications, such as highdata-rate wireless communications, spectroscopy, high-resolution radar, biomedical imaging, security, etc. require compact highpower sources of sub-THz radiation. Traveling wave tube (TWT) amplifiers are the most promising candidates for such sources combining 10–100 W power and wide b andwidth. Here we present the results of design and simulation of a 0.2 THz TWT with a grating slow-wave structure (SWS) and electron-optical system (EOS) with three elliptic-sha ped beams.

Negative Dispersion, Refraction and Backward Polaritons: Impedance Approach

Authors: Davidovich M. V.

Background and Objectives: The dispersion equations of surface plasmon-polaritons are derived for the general case of layered dissipative structures. The waves are classified as gliding with energy flow into structure from vacuum and leakage ones. The dispersion equations and conditions for the existence of slow and fast gliding and leaky waves, as well as forward and backward waves are considered.

Spatiotemporal Structures in an Ensemble of Nonlocally Coupled Nekorkin Maps

Authors: Bogomolov S. А., Rybalova E. V., Strelkova G. I., Anishchenko V. S.

Background and Objectives: Studying chimera states is a subject of special attention among specialists in nonlinear dynamics, and the issue on the mechanisms for implementing chimeras is today one of the topic directions. In the paper we consider the mechanism for realizing a chimera state regime which is based on the so-called “solitary states” (SSC) and is actively discussed by experts. The problem is solved by analyzing the dynamics of a one-dimensional ring of nonlocally coupled discrete-time systems.

Linear Model of Surface Terahertz Plasmons Amplification in Two Parallel Graphene Sheets

Authors: Morozov M. Y., Moiseenko I. M., Popov V. V.

Amplification of terahertz plasmons in a pair of parallel active graphene monolayers is studied theoretically. It is shown that the antisymmetric mode increment of plasmons in the two parallel graphene monolayers may be several times greater than that in a single graphene layer due to deceleration of the antisymmetric plasmon mode as compared to the plasmon mode in a single graphene monolayer.

On the Theory of Synchronization of a Two-Mode Electron Maser with a Hard Excitation

Authors: Adilova A. B., Preobrazhenskaya N. V., Ryskin N. M.

Background and Objectives: Medium-power (10–100 W) THz continuous-wave electron cyclotron masers (gyrotrons) are of great interest for many applications, such as spectroscopy with dynamic nuclear polarization, plasma diagnostics, non-destructive testing, remote detection of radioactive materials, biomedical applications, etc. For these applications, a high frequency stability is required, with the possibility of frequency tuning within 1–2 GHz.

Complex Dynamics and Chaos in the Rabinovich – Fabrikant Model

Authors: Kuznetsov A. P., Kuznetsov S. P., Turukina L. V.

Background and Objectives: In the work we consider a finitedimensional three-mode model of the nonlinear parabolic equation. It was proposed in 1979 by M. I. Rabinovich and A. L. Fabrikant. It describes the stochasticity arising from the modulation instability in a non-equilibrium dissipative medium with a spectrally narrow amplification increment. The Rabinovich – Fabrikant system presents some extremely rich dynamics die to the third-order nonlinearities presented in the equations. The considered system is universal.

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