Generator of broadband noiselike microwave oscillations on turbulent electron beams

Generator of chaotic microwave oscillations on turbulent electron beams has been studied by experimental and theoretical methods. The presence of a magnetic field with sufficiently large amplitude and period leads to the formation of space charge bunches in the electron beam, which results in the generation of broadband noiselike oscillations.     

Ultralow-voltage generator of chaotic microwave oscillations on counterpropagating electron beams

Technical Physics Letters - The new scheme of an ultralow-voltage generator of broadband chaotic microwave oscillations is considered, which operates on counterpropagating turbulent electron beams....     

Small-size ultralow-voltage generator of chaotic microwave oscillations

The scheme of a small-size ultralow-voltage generator of broadband chaotic microwave oscillations is considered. Results of numerical modeling and experimental investigation of the device prototype operating in various regimes are summarized. Good prospects of the proposed ultralow-voltage generator (vircator) are related to the relatively low accelerating voltages (below 1000 V), rather high electron beam currents (up to 800 mA), good efficiency (up to 5%), and small dimensions of the device.     

Ultralow-voltage generator of chaotic microwave oscillations with secondary-emission cathode

A new scheme of an effective ultralow-voltage generator of broadband chaotic microwave oscillations is considered. The device operates on counterpropagating turbulent electron beams, one of which is created by a secondary-emission cathode. Results of an experimental investigation of the device prototype operating in various regimes are summarized. Promising features of the proposed ultralow-voltage oscillator are the relatively low accelerating voltages (below 500 V), increased efficiency (up to 14–15%) compared to analogs, broad band of generated oscillation frequencies, high level of integral output power (up to 35 W), the possibility of fast and easy control over the generation regimes (from almost monochromatic to broadband), and small dimensions of the device.     

Generator of chaotic microwave oscillations based on a high-power bipolar transistor

A chaotic microwave autooscillatory system has been designed, implemented on a high-power bipolar transistor (2T 982 A-2), and studied. The experiments showed stable generation of chaotic oscillations in a 5.26?C5.44 GHz range with a spectral power density of 1.3 × 10^?3 W/MHz.     

A microwave photonic generator of chaotic and noise signals

The transition to chaos in a microwave photonic generator has been experimentally studied for the first time, and the generated broadband chaotic microwave signal has been analyzed. The generator represented a ring circuit with the microwave tract containing a low-pass filter and a microwave amplifier. The optical tract comprised a fiber delay line. The possibility of generating chaotic oscillations with uniform spectral power density in a 3–8 GHz range is demonstrated.     

Studying chaotic microwave oscillations in a TWO with depressed collector

Broadband chaotic oscillations were monitored in a depressed potential collector of a traveling-wave oscillator (TWO). This signal appears due to the oscillations of a virtual cathode, which is formed in the spent electron beam under the action of retarding fields existing in the multistage depressed collector.     

Statistical properties of oscillations of a microwave chaos generator based on a virtual cathode

The statistical properties of signals of a microwave generator of chaotic oscillations based on a virtual cathode have been experimentally studied. It is established that variations in the coefficient of electron beam deceleration not only modifies the spectral characteristics, but also changes the statistical properties of generated signals.     

Ultrabroadband generators of noiselike high-frequency and microwave oscillations with electron feedback

It is experimentally established that oscillators, such as a low-voltage vircator with electron feedback, are characterized by an ultrabroad generation band (up to four octaves and above). The minimum frequency of oscillations is on the order of 50 MHz, while the maximum frequency is about 3–3.5 GHz. The low-frequency part of the spectrum is related to the oscillations of positive ions in the interaction space.     

Generation of chaotic microwave pulses in broadband self-oscillating ring system with ferromagnetic film under the action of external pulse-modulated microwave signal

We have experimentally studied specific features of the generation of chaotic microwave pulse trains in a self-oscillating ring system with nonlinear delay line on surface magnetostatic waves, bandpass filter, and power amplifier on GaAs field-effect transistors under the action of an external pulse-modulated microwave signal occurring outside the band of the generated chaotic signal. It is established that a decrease in the off/duty ratio in the external pulse-modulated microwave signal leads to an increase in this ratio for the chaotic microwave pulses. The integral power of the chaotic microwave signal generated under the pulsed external signal action is increased as compared to the power of signal generated in the autonomous regime.     

Coherent oscillations excited in opposite electron and ion beams of a diaphragmed discharge between hollow electrodes

We have experimentally studied the coherence of oscillations appearing, as a result of the Buneman instability, in a stationary regime of a diaphragmed discharge between hollow electrodes. The degree of coherence of the oscillations grows with the discharge current intensity, which is probably explained by an electrostatic coupling between discharge channels increasing with the amplitude of oscillations.     

基于双混沌系统伪随机比特发生器的研究

研究了基于双混沌系统伪随机比特发生器（CCS-PRBG）生成序列的密码学性质,证明了此二进制序列是i.i.d.序列。理论分析表明,CCS-PRBG可生成具有理想保密性的二进制混沌密码序列。     

Radio-frequency illumination sources based on ultrawideband microgenerators of chaotic oscillations

The task of wideband illumination of objects and surfaces by radiation from artificial noncoherent microwave sources with the aim of subsequent observation by radiometric equipment is considered. The main problem in solving this task consists in creating efficient microwave generators analogous to available sources of lighting in the visible spectral range. We propose to use generators of ultrawideband chaotic oscillations as sources of noncoherent microwave radiation. An experimental prototype of this source taking the form of a SiGe-crystal-based microgenerator of dynamic chaos is described.     

Nonlinear oscillations of thick asymmetric cross-ply beams

Summary The axial and transverse motion of asymmetrically laminated cross-ply beams is coupled due to (i) the non-coincidence of reference and mid-planes and (ii) finite amplitudes. To derive the equations that govern the nonlinear oscillatory behavior of these laminated beams, a spatial deformation satisfying geometric constraints is substituted in the kinetic potential and Hamilton's principle is employed. This leads to three coupled nonlinear second order ordinary differential equations. These equations have quadratic nonlinear terms in addition to usual linear and cubic terms. The existence of these terms does not allow a straight forward solution in the presence of axial and rotatory inertia for nonlinear frequencies/periods. The objective of the present paper is to propose two possible solution methods for computing nonlinear frequencies/periods of asymmetrically laminated cross-ply beams. In both the methods, energy of positive and negative deflection cycles is maintained equal. A few numerical examples are solved to validate the methods. The effect of axial and rotatory inertia on the large amplitude oscillatory behavior is investigated.     

Transient chaotic oscillations of a tethered satellite system

Summary For the simulation of large amplitude motions of thin, visco-elastic tethers connecting two satellites several numerical algorithms were developed recently. However, since we are dealing with highly nonlinear, nearly Hamiltonian multiple degree of freedom systems we typically will have to expect transient chaotic motions if the motion starts in the neighborhood of a saddle point. For tethered satellite systems we have two stable radial and two unstable tangent-to-orbit equilibria. By simulation with a specially adapted finite-element program we show that the asymptotic behaviour of the system strongly depends on the choice of the initial conditions. Thus, starting in the vicinity of an unstable equilibrium, we cannot predict in which of the attractors it settles down finally. A simple tether model by V. Beletsky and D. Pankova is used to demonstrate the fractal nature of the basin boundary of the two attractors.     

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.     

Generation of chaotic oscillations in auto-oscillator based on avalanche transit-time diode

Time series of chaotic oscillations have been observed for the first time in an auto-oscillator for the 8-mm wavelength range based on an avalanche transit-time diode. The noise generator based on this diode has been used as a signal source for a noise radar prototype.     

Reconstruction of chaotic oscillations after passage through linear filters

An analysis is made of the diagnostics of chaotic oscillations generated by a dynamic system and distorted by some linear inertial circuit. A method is developed to reconstruct the initial signal and determine the characteristics of the distorting filter using a time series of the process under study. Pis’ma Zh. Tekh. Fiz. 25, 55–60 (February 26, 1999)