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....     

Tunable generator of broadband chaotic microwave oscillations on turbulent electron beams

A new generator of broadband chaotic microwave oscillations of medium power on turbulent electron beams is proposed, in which it is possible to tune the generation regime. The characteristics of turbulent electron beams have been studied by experimental and theoretical methods. It is established that drag of the electron beam produces its turbulization, which leads to the generation of broadband chaotic microwave oscillations.     

Autostochastic system of coupled microwave generators

Equations are presented describing a system of coupled generators, taking into account the feedback delay and time lag in each partial generator. The delay in the coupling elements between the generators is also taken into account. A numerical analysis of the dynamics of one, two, and three generators is performed. It is shown that chaotization of the oscillations occurs more readily in a coupled system of two or three generators than in the case of a single generator. This is confirmed by the results of experiments on transistor microwave generators. It is found that noise fluctuations can be obtained in a system of three coupled transistor generators over a broad range of frequencies in the centimeter wavelength range. Pis’ma Zh. Tekh. Fiz. 25, 33–38 (April 26, 1999)     

Excitation of high-frequency pressure oscillations during heat exchange with diisopropylcyclohexane

Experimental data are presented on heat transfer with diisopropyl-cyclohexane accompanied by high-frequency pressure oscillations. A hypothesis is advanced relating to the mechanism causing these oscillations.     

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.     

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.     

Method of complex-conjugate matching of microwave noise generators

Translated from Izmeritel'naya Tekhnika, No. 7, pp. 48–50, July, 1988.     

Stepwise current oscillations in tunnel and high-frequency semiconductor diodes

The response of tunnel and high-frequency diodes to an external harmonic signal of large amplitude has been studied. Stepwise current oscillations have been found on the current-voltage characteristics measured at a direct current when an external high-frequency signal is imposed simultaneously on the sample. The frequency of these oscillations decreases with increasing frequency of the external signal. Analogs of the appearance of stepwise current oscillations in semiconductor and other systems are indicated.     

A series of high-frequency EPR spectrometers with microwave and optical detection channels

We describe a series of high-frequency EPR/optically detected magnetic-resonance (ODMR) spectrometers operating in both continuous-wave and pulsed regimes in 2-, 3-, 4-, and 8-mm. The resonance signal can be monitored in both microwave and optical detection channels. The entire series of EPR/ODMR spectrometers has common design features.

     

Development of high-frequency pressure oscillations during heat transfer with forced liquid motion

This article presents the results of an experimental investigation of high-frequency pressure pulsations developing during heat transfer to n-heptane with different flow speeds and pres-sures.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 3, pp. 486–490, September, 1969.     

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.     

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.     

Microstructure evolution of water-oil emulsions in high-frequency and microwave electromagnetic fields

We investigate the impact by high-frequency (HF) and microwave electromagnetic (EM) fields on the microstructure of oil-water emulsions. The laboratory stand for those studies is described. We present the investigation results showing the patterns of the evolution of the water-oil emulsions depending on the EM field parameters and the dielectric properties of the emulsions.     

Nd掺杂对钛酸钡电磁及微波吸收特性影响研究

采用溶胶-凝胶法制备稀土Nd掺杂钛酸钡纳米粉体.采用X射线衍射(XRD)、矢量网络分析仪等手段分别分析表征了样品的微结构和高频电磁特性.结果表明,Nd离子掺杂的钛酸钡样品在750℃温度下退火1h,结晶良好.随着Nd掺杂量的提高,晶粒细化.Nd离子掺杂后,在高频下钛酸钡纳米粉体的介电常数的实部略有减小,虚部峰值得到提高,...     

Spectra of electron oscillations in magnetoplasmadynamic thruster

The intensity and spectra of electron oscillations in magnetoplasmadynamic (MPD) thruster have been experimentally studied. Oscillatory regimes corresponding to various relations between the relative gradients of magnetic field, electron concentration, and residual gas pressure in the vacuum chamber of the experimental setup have been determined. Relationship between the regimes of excitation of electron oscillations, the formation of an azimuthal current, and a change in the plasma flow potential is revealed. Model notions about the instability of plasma flow on low- and high-frequency branches of electron oscillations are developed.     

基于时间加权反馈控制的永磁同步风力发电机混沌振荡研究

研究基于时间加权的反馈控制方法抑制永磁同步风力发电机(PMSG)的混沌行为。以两台PMSGs作为驱动和响应的发电系统,利用相同和不同状态变量间的反馈信息建立不同的动力学方程,分析相同状态变量反馈控制和不同状态变量反馈控制对PMSGs系统混沌振荡行为的影响。发现了相同状态变量反馈控制对PMSGs系统可实现混沌同步行为,而不同状态变量反馈控制对PMSGs系统具有抑制混沌振荡的作用。在周期时间内把这两种反馈控制结合在一起,分析不同时间加权下PMSGs系统的动力学行为,发现时间分数因子和耦合参数的不同取值可使PMSGs系统产生混沌、混沌同步和混沌抑制等动力学行为。数值仿真验证了基于时间加权的反馈控制器对抑制PMSGs系统混沌行为的有效性。研究结果对提高风能利用率,保证电力系统的安全稳定运行具有重要的参考价值。     

Chaotic oscillator with electron feedback and magnetic field at the cathode

The influence of a magnetic field at the cathode on the operation of a low-voltage vircator with electron feedback has been experimentally studied. It is shown that this magnetic field can significantly improve the characteristics and parameters of the vircator, provided that the field lines do not coincide with electron trajectories in the system.     

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.