V. N. Skorokhodov

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.

Dissipative Soliton Oscillator With a Nonlinear Spin Wave Transmission Line and a Signal-to-Noise Enhancer in the Feedback Loop

This study reports on a dissipative soliton oscillator utilizing two nonlinear magnetostatic spin wave (MSW) devices in a feedback loop. Both nonlinear MSW devices [a spin wave transmission line (TL) and a signal-to-noise enhancer (SNE)] operate in the frequency band where three-wave parametric processes are allowed. Self-generation of a complex-modulated MW signal is caused by nonlinearity of the spin wave TL. The SNE carries out a passive locking of the spin wave self-modulation frequencies and forms the dissipative soliton trains. It is shown, that electronic control of a repetition interval and pulse ratio of dissipative solitons is realized by the change of a klystron beam current.

Coherent resonance in klystron oscillator at self-excitation threshold

The phenomenon of coherent resonance in a nonlinear dynamical system based on a delayed-feedback klystron (DFK) oscillator has been experimentally studied. The application of an external white noise signal to the DFK oscillator at the self-excitation threshold leads to the appearance of a resonant response in the system, the maximum of which is attained at a definite power of the external noise. It is demonstrated for the first time that the coherent resonance in response to an external harmonic signal in the microwave range allows the signal-to-noise ratio at the output of a regenerative ring amplifier to be significantly increased.

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.

Experimental and theoretical investigations of the influence of the external noise on dynamics of a klystron oscillator

Experimental and theoretical investigations of the influence of an external noise source on a klystron oscillator with delayed feedback are performed. It is shown that the action of noise leads to suppression of regular, self-modulation, and chaotic signals of the klystron oscillator. The physical mechanism of generation suppression, which is related to the influence of noise on the value of the bunched beam current in the output klystron cavity is revealed. The possibility of the appearance of synchronization induced by noise in a klystron chaotic oscillator subjected to an external noise source is shown theoreticallyk.

Diagnostics of the Generalized Synchronization in Microwave Generators of Chaos

The generalized synchronization of chaos in a system of microwave generators based on klystron amplifiers with delayed feedback has been studied. A modification of the nearest neighbors method for diagnostics of generalized synchronization of chaos in systems with delayed feedback is developed. The efficiency of the modified method for processing experimental data is shown.

Coherent resonance in klystron oscillators

This work presents the data of experimental research of the coherent resonance phenomenon in nonlinear dynamic system — klystron oscillator with delayed feedback. It is shown that when klystron oscillator operates on a threshold of excitation, addition of an external white noise signal leads to excitation of coherent oscillations in system. Maximum of these oscillations is reached at certain power of external noise action.

Suppression of chaotic oscillations in klystron active oscillator

This work presents results of an experimental investigation of the effect of suppressing chaotic oscillations in a five-resonance klystron active oscillator with delayed feedback by external harmonic signal and applying of this effect to generating a periodic sequence of chaotic radio pulses.

KLYSTRON - Generator of Chaotic Radioimpulses

The multicavity klystron oscillator with delayed feedback is able to work in the developed chaos regime (Dmitriev et al., 2003), including generating sequences of chaotic radio pulses. Chaotic radio pulses are fragments of chaotic signals with duration, exceeding the duration of semiperiod of chaotic oscillations. Chaotic radio pulses may be used for information transmission as carrier waves in direct-chaotic systems of communications. These are the systems in which information is introduced into a chaotic signal, generated in SHF interval. Direct-chaotic systems of communications have a number of advantages over traditional systems of information transmission, like stability of spectrum of transmitted broadband chaotic radio-frequency pulses when the duration of these pulses is changed, as well as potentially high speed etc.. The work presents experimental results of producing chaotic radio pulses by multicavity oscillator with delayed feedback by means of the influence of radio-frequency pulse, delivered in the feedback line. In the autonomous mode of klystron work the mode where single- frequency lasing at the boundary of regular self-modulation appearance is chosen. The physical reason for self-modulation and further for chaotic oscillations in klystron oscillator with delayed feedback, like in other oscillators, is the presence of an abrupt dropping section in gain characteristic, resulting from electron regrouping with high rate incoming signal. Nonlinear electron regrouping and delayed feedback of self- sustained resonance oscillation system on the beginning of nonlinearity activity lead to initiation of self-modulation and oscillation chaotization. The conversion into chaos takes place mainly through the sequence of double- period bifurcations. Discharge of outer pulse signal in specified mode causes chaotic oscillations during the pulse

Synchronization of Klystron Active Oscillators in Periodical and Chaotic Regimes

Presented in this paper are the results of experimental research of klystron active oscillators synchronization. It was found out that depending on the nature of the connection and operating modes, mutual synchronization, synchronization with chaos suppression, full synchronization of these active oscillators may be observed