Funtov Alexandr

@sgu.ru

кафедра электроники, колебаний и волн
Федеральное государственное бюджетное образовательное учреждение высшего образования «Саратовский национальный исследовательский государственный университет имени Н.Г. Чернышевского»

Funtov Alexandr


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https://researchid.co/funtovalexandr
15

Scopus Publications

Scopus Publications

  • On planar models of resistive wall amplifier (theory and simulations)
    Saratov State University, Russia, Vladimir Titov, Aleksandr Funtov, Saratov State University, Russia
    Izvestiya Vysshikh Uchebnykh Zavedeniy Prikladnaya Nelineynaya Dinamika, 2025
    The purpose of this paper is to investigate a metamaterial-based planar resistive wall amplifier and to demonstrate the applicability of simplified models for preliminary evaluations. Methods. Two two-dimensional models are considered. The first model constitutes of an infinitely wide sheet beam immersed in a strong longitudinal magnetic field propagating between two identical layers of metamaterial, with the symmetry plane placed along the beam center; the layers of metamaterial and an envelope of parallel metal plates are separated by vacuum gaps. The second model is a periodic structure of thin sheet beams immersed in a strong longitudinal magnetic field propagating through drift channels in an infinite slab of metamaterial. In both cases, the frequency properties of the metamaterial are accounted by the Drude model. The dispersion equations for these models are derived. The transition to one-dimensional linear theory is demonstrated and discussed. The results of linear theory and numerical simulations in CST Particle Studio for each model are compared and analyzed. In numerical simulation, the initial beam density modulation is utilized. In the linear regime, the gain is evaluated by the ratio of the maximum amplitudes of the Fourier transform of the collector current to the emission current. Results and conclusion. The obtained theoretical results show the sensitivity of the metamaterial-based planar resistive wall amplifier performance to geometrical dimensions and properties of the medium. It is shown that by using metamaterial it is possible to obtain a significant increase of the initial beam modulation. A qualitative correspondence between the results of planar linear theory and numerical simulation for both models is shown. The hierarchy of models is formulated.
  • About theory of hybride TWTO and an amplifire with a complex permittivity
    Saratov State University, Aleksandr Funtov
    Izvestiya Vysshikh Uchebnykh Zavedeniy Prikladnaya Nelineynaya Dinamika, 2023
    The purpose of this work is to construct a nonlinear theory of a hybrid between travelling wave tube (TWT) and an amplifier with a complex permittivity. Methods. The following model is considered: an ion-compensated one-dimensional electron beam penetrates the input travelling wave tube section, then flies into a medium with a complex permittivity, and then enters the output travelling wave tube section. A linear theory of this hybrid is constructed, and its results are compared with the results of the well-known linear theory of travelling wave tube. A nonlinear theory of this hybrid was constructed by a modified wave method, and the results were compared with the nonlinear travelling wave tube theory obtained by the classical Ovcharov–Solntsev’s wave method. In addition, to test the limits of applicability of the obtained results, a stationary nonlinear theory of the hybrid was constructed, obtained using the large particle method. The results of this theory were also compared with the stationary nonlinear travelling wave tube theory constructed using the large particle method. Results and conclusion. Based on the results of the developed theories, it is shown that, under certain parameters, the linear theory and nonlinear theories (both by the modified Ovcharov–Solntsev’s wave method and by the large particle method) make it possible to obtain comparable results both in the case of a classical travelling wave tube and for the hybrid under study. It is shown that under certain parameters, due to the resistive instability, the bunching of electrons can be noticeably improved and, as a result, the gain of the hybrid can exceed the gain in a classical travelling wave tube with the same parameters and the same total length of the device in the linear mode of operation. In the nonlinear mode of operation, the specified hybrid, with optimal environmental parameters, can have significantly higher values of output power and efficiency than travelling wave tube with the same value of the space charge parameter and the Pierce parameter.
  • On the Theory of a Hybrid of a Travelling Wave Tube with a Photocathode and an Amplifier with Complex Permittivity
    A. A. Funtov
    Bulletin of the Russian Academy of Sciences Physics, 2021
    A theory is presented for a hybrid of a photocathode with a Travelling Wave Tube (TWT) and an amplifier with complex permittivity. A linear theory of an amplifier with complex permittivity is used in the section with complex permittivity, and the linear theory of TWT is used in the TWT section. Defined motion and the given current are used to construct a nonlinear theory.
  • About theory of extended interaction klystron and drift space in the form of medium with complex permittivity
    Saratov State University, Aleksandr Funtov
    Izvestiya Vysshikh Uchebnykh Zavedeniy Prikladnaya Nelineynaya Dinamika, 2021
    Purpose of this work is to construct a theory of extended interaction klystron with ordinary distributed resonators, but with a drift space in the form of medium with complex permittivity. Methods. For this, a hybrid of extended interaction klystron and an amplifier with a complex permittivity is considered in the framework of the weak signal approximation. Two types of configurations of a extended interaction klystron were considered: with two and three distributed resonators. For a two-resonator klystron with distributed interaction, two cases are considered: without reflections from the ends of distributed resonators and the case when the input binder is fully matched to the external transmission line, and for the second distributed resonator, the so-called condition of critical coupling of the “hot” resonator with the transmission line is satisfied. For a three-resonator klystron with distributed interaction, the case is considered without reflections from the ends of distributed resonators. Results and conclusion. According to the results of the developed theory of a weak signal in a extended interaction klystron with ordinary distributed resonators and a drift space with a complex dielectric constant, by choosing the parameters, it is possible to achieve a greater gain at a length that is shorter than in a conventional extended interaction klystron, all other things being equal. In addition, the presence of an intermediate distributed resonator makes it possible to increase the gain while maintaining the full length of the device.
  • About nonlinear theory of two-cavity klystron with a drift space in the form of medium with complex permittivity
    A. A. Funtov
    Izvestiya Vysshikh Uchebnykh Zavedeniy Prikladnaya Nelineynaya Dinamika, 2020
    The purpose of this work is to construct an approximate nonlinear theory of a klystron amplifier in which a medium with complex conductivity or with metamaterials with negative permittivity is located between the input and output cavities instead of the drift space. Within the framework of the constructed theory, calculate the output characteristics (gain, output power and efficiency) of the described device and compare the results with the classic two-cavity klystron. Methods. Since the principle of operation of a resistive wall amplifier and an amplifier with complex conductivity is precisely the wave process, to construct a nonlinear theory, the Ovcharov–Solntsev wave method is used, the main idea of which is to consider the variable part of the electron passage angle (periodic function of the time of flight) using a series Fourier with few members. The following model is investigated: an ion-compensated cylindrical electron stream penetrates the input resonator, modulates in speed, and flies into a medium with complex permittivity and/or with arbitrary complex conductivity. The electron beam is described in terms of a one-dimensional model. Penetrating the grids of the output cavity, the electron beam induces a high-frequency field in it. Results and conclusion. It is shown that if instead of the drift space between the input and output resonators there is a medium with complex dielectric constant, then the distance between the resonators can be reduced by more than half with an increase in the output characteristics.
  • A Nonlinear Theory of Interaction between Electron Beams and High-Frequency Fields in Media with Complex Conductivity
    A. A. Funtov
    Bulletin of the Russian Academy of Sciences Physics, 2019
    Based on the Ovcharov–Solntsev wave approach, an approximate nonlinear theory is proposed for interaction between electron beams and high-frequency fields in media with complex conductivity.
  • Linear Theory of M-Type Amplifier on Absorption (Amplification and Noise)
    A.A. Funtov
    2018 International Conference on Actual Problems of Electron Devices Engineering Apede 2018, 2018
    A linear theory of the interaction of an electron beam with fields of media with complex conductivity in crossed static electric and magnetic fields is presented. The flux flies between two flat surfaces, generally having complex conductivity. The models of an infinite thin beam and a beam of finite thickness are investigated. The noise coefficient for a lamp on an M-type absorption with a beam of finite thickness is estimated.
  • Noise in resistive-wall amplifier of m-type with «thick» beam
    Saratov State University, A. A. Funtov
    Izvestiya Vysshikh Uchebnykh Zavedeniy Prikladnaya Nelineynaya Dinamika, 2018
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  • Noise in resistive-wall amplifier of m-type with «thick» beam
    Izvestiya Vysshikh Uchebnykh Zavedeniy Prikladnaya Nelineynaya Dinamika, 2018
  • Wave processes in the electron beam in crossed static electric and magnetic fields as it moves in a medium with a complex conductivity
    Saratov State University, Funtov A. A.
    Izvestiya Vysshikh Uchebnykh Zavedeniy Prikladnaya Nelineynaya Dinamika, 2017
    ВОЛНОВЫЕ ПРОЦЕССЫ В ЭЛЕКТРОННОМ ПОТОКЕ В СКРЕЩЕННЫХ СТАТИЧЕСКИХ ЭЛЕКТРИЧЕСКИХ
  • Noises in resistive wall amplifier, caused by fluctuations in the electron beam
    Saratov State University, D. I. Trubetskov, A. A. Funtov, Saratov State University, N. V. Chizhmotrya, Saratov State University
    Izvestiya Vysshikh Uchebnykh Zavedeniy Prikladnaya Nelineynaya Dinamika, 2017
  • About consideration of electron transverse motions in resistive wall amplifier
    National Research Saratov State University, A. A. Funtov
    Izvestiya Vysshikh Uchebnykh Zavedeniy Prikladnaya Nelineynaya Dinamika, 2016
  • Some questions of the theory of resistive wall amplifier m-type
    Izvestiya Vysshikh Uchebnykh Zavedeniy Prikladnaya Nelineynaya Dinamika, 2015
  • Interference amplification in an electron-wave tube (Linear Theory)
    D. I. Trubetskov, A. V. Titov, A. A. Funtov
    Technical Physics Letters, 2013
  • ABOUT APPROXIMATE ANALYTICAL SOLUTIONS OF LOTKA-VOLTERRA EQUATIONS
    Izvestiya Vysshikh Uchebnykh Zavedeniy Prikladnaya Nelineynaya Dinamika, 2011