R. A. Filatov

Influence of background gas ionization on oscillations in a virtual cathode with a retarding potential

The effect of mobile ion background on the dynamics of a planar virtual cathode with retarding field is investigated. The ions appear in the diode gap due to ionization of a neutral gas by the electron beam. Detailed examination of the self-consistent processes of the virtual cathode dynamics, gas ionization, and ions motion is performed using the particle-in-cell simulation. It is shown that the presence of ions leads to the virtual cathode neutralization, its displacement, and subsequent anew formation. The microwave generation has the form of a sequence of pulse packets, whose duration depends on the value of the retarding potential and the kind of gas.

Experimental and Theoretical Investigations of Stochastic Oscillatory Phenomena in a Nonrelativistic Electron Beam with a Virtual Cathode

Results are presented from experimental investigations of oscillatory phenomena in an electron beam with a virtual cathode in a diode gap with a decelerating field. Experiments have revealed a stochastic broadband generation of the microwave oscillations of a virtual cathode in a decelerating field. Numerical simulations based on a simple one-dimensional model have shown that the onset of the stochastic generation and the broadening of the oscillation spectrum with increasing beam deceleration rate are governed by the processes of regrouping of the electrons in a beam with a virtual cathode.

Spatiotemporal Chaos Synchronization in Beam-Plasma Systems with Supercritical Current

It is established that coupled beam-plasma systems with supercritical current can feature the phenomenon of chaotic synchronization. As the coupling between subsystems increases, a distributed beam-plasma system exhibits the transition from asynchronous behavior via phase synchronization to the state of complete chaotic synchronization. The phenomenon of chaotic synchronization is studied using a method developed previously on the basis of the introduction of a continuous manifold of phases of the chaotic signal.

Dynamics of an Electron Beam with a Virtual Cathode in a Vircator without a Magnetic Field and with Drift Space Filled by Neutral Gas

The physical processes in a vircator without an external magnetic field and with a drift space filled by neutral gas are studied. Three typical dynamic regimes are found: (1) the suppression of virtual cathode oscillations, (2) pulse generation, in which the suppression and resumption of virtual cathode oscillations are observed, and (3) continuous virtual cathode generation. The frequency dynamics of the vircator’s output radiation is investigated for the last case, and it is shown that the generation frequency of the vircator can rise when the gas pressure exceeds a certain critical value.

Simulation of oscillatory processes in a beam-plasma system with a virtual cathode in gas-filled interaction space

Physical processes occurring in an intense electron beam with a virtual cathode in an interaction space filled with neutral gas are studied in a two-dimensional model. A mathematical model is proposed for investigating complicated self-consistent processes of neutral gas ionization by the beam electrons and the dynamics of an electron beam and heavy positive ions in the common space charge field with allowance for the two-dimensional motion of charged particles. Three characteristic dynamic regimes of the system are revealed: complete suppression of oscillations of the virtual cathode as a result of neutralizing its space charge by positive ions; the pulsed generation regime, in which the ions dynamics repeatedly suppresses and restores the virtual cathode oscillations; and the continuous generation regime with an anomalously high level of noisy oscillations.

Experimental and Theoretical Study of Chaotic Microwave Oscillations and Pattern Formation in Non-relativistic Electron Beam with Virtual Cathode

Results are presented from experimental and numerical study of oscillatory phenomena in electron beam with virtual cathode (VC) in diode gap with decelerating field. Experiments have revealed a chaotic broadband generation of the microwave oscillations of VC. Numerical simulations based on a simple PIC model have shown that the onset of the chaotic generation with increasing beam deceleration rate are governed by the processes of regrouping of the electrons in the beam with VC

Oscillatory processes in gas discharge with overcritical beam current

Within the limits of two dimensional numeric model physical processes of oscillations of virtual cathode in drift space, filled with neutral gas, are investigated.

Non-stability of symmetric state in the system of countercurrent electron streams

In the present report the increasing of space-charge density of countercurrent streams, causing losses in stability of symmetric states within the limits of two dimensional numeric model was investigated.

Chaotic Radiopulse Generator on the Basis of Electron Beam with Virtual Cathode

Presented in this paper is the novel system for chaotic pulses generation based on electron beam with virtual cathode in retarding field. Processes numerical simulation in the generator offered has been carried out. In order to consider chaotic pulse generation mode, we have developed mathematical model taking into account gas impact ionization by electron flow. The dependence of output signal characteristics on system control parameter has been examined.

Chaotic synchronization in distributed beam-plasma systems with supercritical current

Chaotic synchronization is found to arise in coupled beam-plasma systems with supercritical current. It is shown that, with increasingly stronger coupling, such systems pass from asynchronous behavior via phase synchronization to complete synchronization. Chaotic synchronization is studied according to a method based on the introduction of a continuous set of phases of the chaotic signal. In the case of unidirectional coupling, a generalized chaotic synchronization mode is observed. The mechanism of its emergence in the beam-plasma systems is investigated via the modified-system method.