Yu. D. Zharkov

Experimental study of complex dynamics in a delayed-feedback multiple-cavity klystron self-oscillator

The main characteristics of a delayed-feedback multiple-cavity klystron oscillator with various oscillation modes (single-frequency oscillations, as well as regular and chaotic self-modulations) are studied experimentally. Maps of dynamic modes on the beam current-accelerating voltage plane are presented. Basic scenarios of transition to chaos are considered. As the beam current and amount of feedback increase, regular and chaotic oscillation modes are found to alternate in a complex manner. It is shown that one can significantly increase the power of chaotic oscillations by appropriately tuning the control parameters.

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.

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.

Multiple cavity klystron - a source of chaotic microwave radiation

A number of applications, such as charged particle accelerators, microwave plasma heating and modem communication systems, require powerful sources of noise-like microwave radiation with a relatively wide band, that is achieved in the regime of chaotic oscillations. Among such sources a delayed feedback oscillator based on a multiple cavity klystron amplifier seems to be one of the most promising due to high power level and high efficiency. This report presents the results of theoretical and experimental investigation of a delayed feedback klystron oscillator in the regimes of single-frequency, self-modulational and chaotic oscillations.

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.

Nonlinear dynamics in a multiple cavity klystron oscillator with delayed feedback

In this presentation, the theoretical and experimental research of a delayed feedback klystron oscillator, both in autonomous and non-autonomous modes under external driving are discussed.

Generalized synchronization in a system of coupled klystron chaotic oscillators

The phenomenon of generalized chaotic synchronization has been studied in a system of two unidirectionally coupled chaotic oscillators modeling two-sresonator klystron autooscillators. A mechanism explaining the observed behavior is presented.

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

Generation and control of wide-range microwave chaotic signals TWT-generator

The paper presents the results of experimental research on the generation of wide-range microwave chaos based on TWT-generator. Researched and detected a chaotic signal absolute suppression mode external harmonic input of a certain frequency and power. This effect allows for impulse modulation of the input signal to provide the generation of chaotic microwave radio pulses.