Results 151 to 160 of about 2,693 (187)
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On the current through a virtual cathode
Technical Physics, 2003Two existing opinions about the current passing through a virtual cathode in a closed equipotential cavity are considered: (i) the current is always smaller than half the limiting current (as follows from the steady-state consideration) and (ii) the current oscillates in time about the mean value that is exactly equal to the limiting current (as ...
A. E. Dubinov, I. A. Efimova
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Proceedings International University Conference 'Electronics and Radiophysics of Ultra-High Frequencies' (Cat. No.99EX356), 2003
In a system with a VC the oscillation of the virtual cathode results in parametric excitation of oscillations of the electrons and in phase modulation of the electron flow. In this case, the width of the electron bunch is determined by the space charge field and by the anode transparency.
V.P. Grigoryev, T.V. Koval
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In a system with a VC the oscillation of the virtual cathode results in parametric excitation of oscillations of the electrons and in phase modulation of the electron flow. In this case, the width of the electron bunch is determined by the space charge field and by the anode transparency.
V.P. Grigoryev, T.V. Koval
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Coaxial Virtual Cathode Enhancement
2004Abstract : Traditionally, the radiated microwave frequency in a coaxial vircator is considered to be determined primarily by the virtual cathode oscillation frequency and the electron reflection frequency. In this paper, some experiments showing different results are reported. Particularly, the E-beam is observed to play an important role in the cavity
J. Mankowski, M. Kristiansen
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Analysis and simulation of virtual cathode oscillations
The Physics of Fluids, 1986A nonlinear mechanism for virtual cathode oscillations is derived from an analysis of a cold plasma fluid model. Frequency scalings and field wave shapes are predicted. These are compared with extensive numerical simulation studies of non-neutral electron beams using both one- and two-dimensional particle-in-cell codes.
Abraham Kadish +2 more
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On Dynamics of Metastable Electrons in a Virtual Cathode
Radiophysics and Quantum Electronics, 2002We propose a simple model for dynamics of the earlier detected metastable electrons oscillating near a virtual cathode. It was found that their behavior is similar to the dynamics of a reversed pendulum with a vibrating suspension, which was studied by P. L. Kapitsa. The number of metastable electrons is estimated using the method of large particles.
A. E. Dubinov +2 more
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Virtual cathode oscillator (vircator) modes
12th International Conference on Microwaves and Radar. MIKON-98. Conference Proceedings (IEEE Cat. No.98EX195), 2002Vircators as high-power microwave sources have been investigated for twenty years now. Computer simulations are important tools for vircator performance investigations. However, such simulations do not show the mechanisms involved. Two basic mechanisms are usually discussed: Bridges and Birdsall oscillations and Barkhausen-Kurz oscillations.
W. Czarczynski, J. Sobanski
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To the theory of feedback in generators with virtual cathode
13th International Crimean Conference Microwave and Telecommunication Technology, 2003. CriMiCo 2003., 2003The self-consistent nonstationary model of beam feedback in devices with virtual cathode (VC), which uses the flow instability in the cathode-anode gap and nonlinear particle interaction with VC oscillations is presented. Nonlinear process involving both areas is featured as an interaction between coupled Van der Pol-Duffing oscillators.
I.I. Magda +4 more
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Experiment for teaching virtual cathode in nerve conduction studies
Muscle & Nerve, 2021AbstractIntroduction/AimsThe virtual cathode (VC) is a site near the anode where the nerve can be stimulated. Costimulation of neighboring nerves via the VC can affect recording and interpretation of responses. Hence, it is important to teach trainees the concept of the VC. The VC has been demonstrated previously with subtle changes in response latency,
Sanjeev D. Nandedkar +2 more
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Virtual Cathode Oscillator Component Optimization
Conference Record of the 2006 Twenty-Seventh International Power Modulator Symposium, 2006Recent research efforts at TTU include a simple aluminum cathode for E-beam generation in a virtual cathode oscillator (vircator) [1]. As a continuation of these results, we are fabricating and testing several different types of cathodes for the vircator driven by a Marx generator and a pulse forming line (400 kV, 60 ns, 30 ?).
Yeong-Jer Chen +3 more
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Characteristics of Virtual Cathode Generated by Common Thermionic Cathodes
A vacuum virtual cathode theory is developed, and analytical expressions for the virtual cathode characteristics are derived under different controlled parameter modes. Considering the ratio of electron collection to emission current (jC/jE) as an integral variable, the virtual cathode potential is solely a function of jC/jE and the heating temperatureJian-quan Li +4 more
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