Generation of single chaotic microwave pulses in a self-oscillating ring system with ferromagnetic film under the action of external noise

The generation of single chaotic microwave pulses in a self-oscillating ring system with ferromagnetic film under the action of external narrow-band noise microwave signal occurring outside the band of frequencies of the chaotic microwave signal was observed. Chaotic generation emerged due to the parametric instability of the magnetostatic surface wave in the ferromagnetic film, whereas formation of single chaotic microwave pulses was caused by the absence of complete suppression of chaos under the action of narrowband noise.     

Wideband chaotic microwave signal generation in a ring system with a nonlinear delay line on coupled ferromagnetic films

Various regimes of chaotic signal generation have been studied in an self-oscillating ring system with a wideband nonlinear delay line based on coupled ferromagnetic films, in which magnetostatic backward volume waves (MSBVWs) are excited. It is shown for the first time that the simultaneous excitation of two waves in the coupled films leads to the appearance of a falling part in the dynamic characteristic of the MSBVW delay line and the generation of a broadband chaotic signal with a continuous spectrum. Under certain conditions, the ring exhibits a regime of intermittency, in which broadband chaotic signals with both continuous and discrete spectra are generated.     

Generation of chaotic microwave pulses with the help of passive synchronization of spin wave self-modulation frequencies in self-oscillatory ring systems

Passive synchronization (PS) of spin wave self-modulation frequencies of a chaotic microwave signal has been observed for the first time in a self-oscillatory ring system involving a nonlinear passive element with saturable absorption. The development of PS led to the generation of a periodic train of chaotic microwave pulses with an off/duty ratio exceeding 20. It is established that the repetition period of chaotic microwave pulses can be controlled by changing gain in the ring system.     

Generation of chaotic dissipative solitons in active ring resonator with one-dimensional periodic ferromagnetic miscrostructure

Generation of chaotic dissipative solitons has been observed in an active ring resonator with one-dimensional periodic ferromagnetic microstructure comprising a single-crystalline film of yttrium iron garnet (YIG) with a lattice of grooves oriented perpendicular to the direction of propagation of a magnetostatic surface wave (MSSW). A quasi-periodic train of chaotic dissipative solitons was generated in this system under the conditions of three-magnon processes of MSSW decay due to the passive synchronization (PS) of spin wave self-modulation in a frequency band corresponding to the first bandgap. The PS onset was caused by the saturable absorption of microwave signals within the bandgap of the MSSW transmission line.     

Generation of chaotic microwave pulses in a ring system based on a klystron power amplifier and a nonlinear delay line on magnetostatic waves

The autonomous generation of stationary chaotic microwave pulse trains in a self-oscillating ring system with a multicavity klystron power amplifier operating in a small-signal regime and a wideband non-linear delay line on surface magnetostatic waves has been experimentally studied. It is established that the characteristics of generated chaotic microwave pulses can be controlled by varying the electron beam current and accelerating voltage in the klystron.     

Generating dynamic microwave chaos in self-oscillating ring system based on complementary metal-oxide-semiconductor structure

We have designed, implemented, and studied a chaotic self-oscillating system based on a monolithic integrated circuit on a silicon substrate. Experimental prototypes demonstrated stable generation of chaotic microwave oscillations with a maximum spectral power density in a frequency range of 2.8–3.8 GHz.     

Studying dynamic chaos in microwave ring generators based on normally magnetized ferromagnetic film

Technical Physics Letters - We present results of an experimental investigation of the transition to a microwave dynamic chaos regime in ring oscillators based on normally magnetized yttrium iron...     

Transition to phase synchronization in a system with periodic dynamics under the action of a chaotic signal

Intermittent behavior has been studied near the boundary of phase synchronization in an autooscillatory system with periodic dynamics under the action of an external chaotic signal. It is shown that the intermittency obeys the same scenario as that observed in the case of interaction between two coupled chaotic oscillators.     

Generation of dissipative structures in self-oscillating ring systems upon parametric interaction of spin waves

A quasi-periodic sequence of pulses in a self-oscillating ring system with a resonant amplifier and a ferromagnetic film has been generated upon three-wave parametric interaction of spin waves. It is established that the generated pulses are analogs of dissipative bright solitons, which are formed as a result of competition between amplification and loss, as well as between time dispersion and nonlinearity. To describe the mechanism of formation of these structures, we have proposed a model in the form of three parametrically coupled differential equations with amplification and a differential equation of linear oscillator. Under certain assumptions, this model has analytical solutions in time in the form of structures with a profile similar to that of bright solitons.     

Generation of microwave oscillations in a superconducting tunnel mesa-structure with a ferromagnetic insulator interlayer

Spin-polarized current in thin-film tunnel mesa-structures formed by epitaxial cuprate superconducting (YBa₂Cu₃O_7–δ) and manganite (LaMnO₃) films and an upper superconducting Au–Nb bilayer is studied experimentally. Intrinsic narrow-band generation in the microwave range is reported. Its frequency is tuned by the bias voltage and an external magnetic field.     

Study of the reflectance of an aluminum film under simultaneous action of current pulses and laser radiation

We have experimentally observed a reversible increase in the reflectance of aluminum at a wavelength of 308 nm during the passage of an electric current pulse with a density of up to 100 MA/cm². It is suggested that the effect is explained by partial reflection of the incident radiation by free electrons injected into the conduction band of an oxide film on the metal surface during the passage of a current pulse.     

Excitation of a potentially self-oscillating state in an oscillator with delay and inertia exposed to the simultaneous action of regular and chaotic signals

An analysis is made of the possibility of inducing a potentially self-oscillating state in a bistable self-oscillating system exposed simultaneously to regular and chaotic signals, as applied to the covert transfer of information in a binary computational system. A system of nonlinear differential difference equations is derived, which describe the behavior of an oscillator with delay and inertia under the action of complex oscillations in a given time interval. It is shown numerically that even when a potentially self-oscillating state is not excited by an external regular signal, stochastic oscillations, as well as providing a masking effect, may function as an additional stimulus to transfer the system to the basin of attraction of a potentially selfoscillating attractor. Pis’ma Zh. Tekh. Fiz. 23, 66–71 (July 26, 1997)     

Equations of a time-delay system under external action reconstructed from time series

A new method is proposed for the use of time series for reconstructing the equations of a system with time-delay feedback under an external action. The performance of the proposed method is illustrated by application to short noisy time series of a model system under external actions of various types.     

Transformation of bistable chaotic oscillations in triggers of a ring system

Equations describing a ring system of three unidirectionally coupled Chua oscillators (subsystems) are presented. Numerical analysis is performed in the case in which only one subsystem is autooscillatory. It is shown that non-auto-oscillatory subsystems (simplified to single-shot trigger type) exhibit complication of circuit oscillations that is accompanied by multiplication of the oscillation frequencies and expansion of the generated spectrum.     

Reconstructing nonautonomous system models with discrete spectrum of external action

We describe a method of constructing model differential equations using the scalar chaotic time series for systems under external action with discrete spectrum. The approach is based on taking into account the explicit time dependence in the structure of a model and approximating this dependence by trigonometric series. The proposed method is verified by numerical experiments on standard nonlinear systems driven by periodic and quasiperiodic factors of various types.     

Determination of the moments of inertia with a self-oscillating electromechanical system

A method is considered for measuring the moments of inertia of products by the frequency of undamped oscillations in an electromechanical system with a contactless electrical machine having an active rotor. A measuring procedure is given and the results of experimental studies are reported.Translated from Izmeritel'naya Tekhnika, No. 4, p. 31–32, April, 1994.     

Experimental study of the effect of external signal on microwave oscillations in a nonrelativistic electron beam with virtual cathode

The effect of an external harmonic signal on the characteristics of microwave generation in a non-relativistic electron beam with virtual cathode (VC) formed in a static retarding electric field (low-voltage vircator system) has been experimentally studied. A significant increase in the vircator generation power is observed when the frequency of the external signal is close to the frequency of VC oscillations. At large detunings, a broadband chaotic generation is observed.     

Thermoelastic state of a conducting cylinder under the action of surface electromagnetic pulses

We pose a mathematical dynamic boundary-value problem of electromagnetothermoelasticity for a long continuous conducting cylinder and propose a method for the solution of the formulated boundary-value problems of electrodynamics and thermoelasticity based on the polynomial approximation (in the radial coordinate) of the axial and circular components of the vector of magnetic-field intensity, temperature, and radial stresses. The results of the numerical analysis of the problem for copper and steel cylinders are presented.Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 40, No. 2, pp. 45–52, March – April, 2004.