A.B. Pavelyev

Russian Academy of Sciences, Moskva, Moscow, Russia

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Publications (20)10.33 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A 24 GHz 3 kW CW gyrotron (n=2) with permanent magnet and microwave source based on the gyrotron are developed. The source incorporating a set of power supplies, transmission line, and PC-based RF power control extends a line of gyrotron systems designed as a versatile and user friendly tool for research in microwave energy applications.
    No preview · Conference Paper · Jan 2004
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    ABSTRACT: Main results of experimental study of the 140 GHz/ 1,5 MW coaxial gyrotron are summarized. High selective properties of the coaxial cavities and a possibility to increase considerably the efficiency of a coaxial gyrotron only by applying independently an appropriate voltage on its electrodes (without any design modification) have been confirmed. A successful use of the two-potential connection scheme for the frequency step tuning and output power modulation in a coaxial gyrotron has been also demonstrated.
    No preview · Article · Jan 2003
  • [Show abstract] [Hide abstract]
    ABSTRACT: Main results of experimental testing of the 140 GHz/1.5 MW coaxial gyrotron are summarized. High selective properties of the coaxial cavities and a possibility to increase considerably the efficiency of a coaxial gyrotron only by applying independently an appropriate voltage on its electrodes (without any design modification) have been confirmed. Successful uses of the two-potential connection scheme for the frequency step tuning and output power modulation in a coaxial gyrotron has been also demonstrated.
    No preview · Article · Dec 2002 · International Journal of Infrared and Millimeter Waves
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    ABSTRACT: The main results of the experimental study of a 140 GHz/1.5 MW coaxial gyrotron are summarized. The highly selective properties of the coaxial cavities and the possibility for controlling the electron beam parameters by means of changing the potential of the inner rod have been confirmed.
    No preview · Conference Paper · Feb 2002
  • [Show abstract] [Hide abstract]
    ABSTRACT: Main results of experimental testing of the 140 GHz/1.5 MW coaxial gyrotron (Russian version of the joint Russian-German coaxial gyrotron) are summarized. Highly selective properties of the coaxial cavities and a possibility to increase considerably the efficiency of a coaxial gyrotron by applying independently an appropriate voltage on its electrodes (without any design modification) have been confirmed. A successful use of the two-potential connection scheme for the frequency step tuning and output power modulation in a coaxial gyrotron have also been demonstrated
    No preview · Conference Paper · Feb 2001
  • V. E. Zapevalov · A. B. Pavelyev · V. I. Khizhnyak
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    ABSTRACT: It is shown that the efficiency of a coaxial gyrotron can be increased considerably by applying only independently appropriate voltages to its electrodes (without modifying design). The proposed scheme is also suitable for stepwise frequency tuning and for deep modulation of output power.
    No preview · Article · Jul 2000 · Radiophysics and Quantum Electronics
  • O. Dumbrajs · V.I. Khizhnyak · A.B. Pavelyev · B. Piosczyk · M.K. Thumm
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    ABSTRACT: A design of a new powerful high-frequency short-pulse coaxial-cavity harmonic gyrotron operating at first, second, and third harmonic is presented. The design includes the analysis of mode competition between the fundamental and higher harmonic modes, as well as the investigation of the possibility of the corresponding fast frequency tuning of the gyrotron by changing the accelerating voltage. The possibilities of modification of the existing coaxial cavity gyrotron operating at present at the Forschungszentrum Karlsruhe (FZK) for operation at the second harmonic are discussed. Potentialities of such gyrotrons for plasma physics applications are noted.
    No preview · Article · Jul 2000 · IEEE Transactions on Plasma Science
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    ABSTRACT: Some results of experimental testing of the 140 GHz/1.5 MW coaxial gyrotron with a lower level of ohmic losses in the cavity are presented and some nearest plans concerning the development of coaxial gyrotrons at IAP RAS are outlined. Results of investigation of the natural energy recovery scheme and frequency step tunability for coaxial gyrotron are discussed. The report presents also the project of the future superpower coaxial gyrotrons with an acceptable (for CW-regime) level of the heat load density
    No preview · Conference Paper · Feb 2000
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    ABSTRACT: Measurements on a coaxial gyrotron equipped with modified components have been performed. In experiments a maximum RF-output power of 2.2 MW with an output efficiency of 28% has been obtained. A maximum efficiency of 30% (48% with depressed collector) has been achieved at the nominal output power of 1.5 MW. The mechanical stability of the insert under operating conditions has been found to be within ±0.03 mm which is sufficiently low for stable long pulse operation. Parasitic low frequency oscillations have been identified to be generated either inside the mirror box (474/386 MHz) or in the cathode region (21/82 MHz)
    No preview · Conference Paper · Feb 2000
  • O. Dumbrajs · Ch.T. Iatrou · A.B. Pavelyev · B. Piosczyk · M. Thumm
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    ABSTRACT: Some design considerations related to wall losses and mode competition in an ITER relevant coaxial cavity gyrotron are presented. New possibilities of heat redistribution and of reduction of mode competition by means of an insert with variable depth of corrugations along the longitudinal direction of the cavity are discussed
    No preview · Conference Paper · Feb 2000
  • [Show abstract] [Hide abstract]
    ABSTRACT: Some results of experimental testing of the 140 GHz/ 1,5 MW coaxial gyrotron (Russian version of the joint Russian-German coaxial gyrotron) with a lower level of ohmic losses in the cavity are presented and some nearest plans concerning the development of coaxial gyrotrons at IAP RAS are outlined. The report presents also the project of the future superpower coaxial gyrotrons with an acceptable (for CW-regime) level of the heat load density
    No preview · Conference Paper · Sep 1999
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    ABSTRACT: A 140-GHz, 1.5-MW, TE<sub>28,16</sub>-coaxial cavity gyrotron with a dual RF beam output has been designed, built, and tested. For the first time, the generated RF power has been split into two parts and coupled out through two RF output windows in order to reduce the power loading in the windows. The quasioptical output system is based on a two-step mode conversion scheme. First, the cavity mode TE<sub>-28,16 </sub> is converted into its degenerate whispering gallery mode TE<sub>+76,2</sub> using a rippled-wall mode converter. Then, this mode is transformed into two TEM<sub>00</sub> output wave beams. A maximum rf output power of about 950 kW with an output efficiency of 20% has been measured. According to numerical calculations, an rf power above 1.5 MW is expected to be generated in the cavity. Even if all losses are taken into account, a discrepancy between experiment and calculations remains. The power deficit seems to be partly caused by the influence of the stray radiation captured inside the tube. However, the two main reasons are probably an incomplete mode conversion from TE<sub>-28,16</sub> to TE<sub>+76,2</sub> and a large energy spread of the electron beam due to trapped electrons. An increased amount of captured stray radiation resulted in a reduced stability of operation. A single-stage depressed collector was used successfully, increasing the RF output efficiency from 20% to 29%
    No preview · Article · Jul 1998 · IEEE Transactions on Plasma Science
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    ABSTRACT: The progress in the development of a 1.5 MW coaxial cavity gyrotron operated at 140 and 165 GHz is reported. The basic operating problems have been investigated in experiments with an axial rf-output. With two different coaxial cavities designed for operation in the TE28,16 and the TE31,17 mode at 140 and 165 GHz, respectively, an rf-output power close to 1.2 MW has been measured with an output efficiency of about 27 %. In these experiments the results agree very well with results of multimode calculations. A dual rf-beam output has been investigated with the 140 GHz, TE28,16 - coaxial gyrotron. The generated rf-power has been split internally in two parts for the first time and coupled out through two rf-output windows. The results - 0.95 MW output power with 20% output efficiency - prove in principle the usability of the internal splitting of the rf-beam. However, the efficiency of the rf-output system has to be improved in order to reduce the amount of rf power captured inside the gyrotron tube which is one reason for the observed low efficiency. A single-stage depressed collector was operated successfully, increasing the rf-output efficiency from 20 % to 29 %. Next the gyrotron will be operated in the TE31,17 mode at 165 GHz with a single rf-output window using a phase correcting mirror. To improve the properties of the electron beam the emitter has been replaced and the alignment of the gun has been improved.
    No preview · Article · Jan 1998
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    ABSTRACT: The design of a 1.5-MW, 140-GHz, TE-<sub>28,16</sub>-coaxial cavity gyrotron is presented and results of experimental operation are given. A cavity with a cylindrical outer wall and a radially tapered inner rod with longitudinal corrugations was used. A maximum output power of 1.17 MW has been measured in the design mode with an efficiency of 27.2%. Single-mode operation has been found over a wide range of operating parameters. The experimental values agree well with the results of multimode calculations. Frequency-step tuning has been performed between 115.6 and 164.2 GHz. In particular, an output power of 0.9 MW has ben measured in the TE<sub>25,14</sub> mode at 123.0 GHz and 1.16 MW in the TE<sub>32,18</sub> mode at 158.9 GHz. At frequencies its with strong window reflections the parameter range for which stable operation is possible is reduced significantly. In order to obtain results relevant for a technical realization of a continuously operated gyrotron, a tube with a radial radio frequency (RF)-beam output through two output windows and a single-stage depressed collector has been designed and is under fabrication. A two-step mode conversion scheme-TE- <sub>28,16</sub> to Te<sub>+76.2</sub> to TEM<sub>00</sub>-which generates two narrowly directed (60° at the launcher) output wavebeams has been chosen for a quasioptical (q,o) mode converter system. A conversion efficiency of 94% is expected
    No preview · Article · Jul 1997 · IEEE Transactions on Plasma Science
  • O. Dumbrajs · AB Pavelyev
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    ABSTRACT: A general theory describing symmetry breaking in coaxial cavities is presented. General expressions are derived for frequency shift and for ohmic losses in both the inner conductor and the resonator wall in an eccentric coaxial cavity. The theory is illustrated in the case of the TE mode 140 GZz coaxial high-power 28,16 gyrotron developed jointly by the Institute of Applied Physics in Nizhny Novgorod, Russia, and the Forschungszentrum Karlsruhe, Karlsruhe, Germany.
    No preview · Article · Mar 1997 · International Journal of Electronics
  • Christos T. Iatrou · Stefan Kern · Alexander B. Pavelyev
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    ABSTRACT: This paper investigates coaxial gyrotron cavities with longitudinal slots on the inner conductor as a means to reduce the number of possible competing modes. In the analytic theory the corrugated surface is treated as a homogeneous impedance surface (“impedance corrugation”) to obtain simple formulas for the characteristic equation of the eigenmodes, for the electromagnetic fields and the wall losses. The developed model applies if the number of slots is sufficiently high (cutoff wavelength much larger than the corruption period). The characteristic equation in terms of the ratio C of the outer wall radius to the inner conductor radius is solved numerically to determine a range of eigenvalues and C where the eigenvalue curves are monotonically decreasing. In such a region a cavity having its inner conductor downtapered (radius decreasing toward the cavity output) can be used to reduce the diffractive quality factors of several modes, leaving the working mode undisturbed and without favoring other modes. In addition the electromagnetic field profiles are investigated, and in particular it is shown that for certain cavity parameters a mode could have its energy concentrated close to the inner conductor. As a check on the validity of the theoretical approximations, simulations with the MAFIA code are carried out. These give good agreement with the results of the analytic equations
    No preview · Article · Feb 1996 · IEEE Transactions on Microwave Theory and Techniques

  • No preview · Article · Jan 1996
  • V. K. LYGlN · V. N. MANUlLOV · A. N. KUFTIN · A. B. PAVELYEV · B. PIOSCZYK
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    ABSTRACT: A 50 A electron gun with a beam power of 4-5MW for a 1-5MW, 140GHz coaxial gyrotron has been designed, manufactured and tested. An axial rod close to the ground (anode) potential is surrounded by the cathode. The gun is of the diode type with no independent adjustment of the velocity ratio α. Therefore only a low influence of the mechanical tolerances on a can be accepted. The beam properties have been measured using scaled-down parameters. The experimental values of [he velocity ratio agree well with calculation. The measured velocity distribution shows a transverse velocity spread δβ⊥≤15%.
    No preview · Article · Aug 1995 · International Journal of Electronics
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    ABSTRACT: A general theory is developed for self-consistent calculations of mode competition in a gyrotron with nonfixed axial structure of the RF field for arbitrary cyclotron harmonics. The theory is applied to the gyrotron operating at the Kernforschungszentrum Karlsruhe with a frequency of 150 GHz. The formalism presented allows a self-consistent calculation of mode competition for the operating and parasitic modes at the cyclotron resonance at arbitrary harmonics. Specific calculations are carried out for the cases n <sub>0</sub>=1, n <sub>1 </sub>=2 and n <sub>0</sub>=2, n <sub>1</sub>=1. It is emphasized that the formalism considered applies only to the case in which the azimuthal orthogonality condition is satisfied: n <sub>0</sub> m <sub>1</sub>≠ n <sub>1</sub> m <sub>0</sub>. There are circumstances when this condition is not satisfied
    No preview · Article · Jul 1990 · IEEE Transactions on Plasma Science
  • O. DUMBRAJS · G. S. NUSINOVICH · A. B. PAVELYEV
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    ABSTRACT: A general method is developed for the analysis of mode competition in a gyrotron with tapered external magnetic field. Exploratory calculations show strong dependence of the operating regime of a gyrotron on tapering of the magnetic held. Detailed results are presented for the gyrotron operating at the Kernforschungs-zentrum Karlsruhe with frequency 150 GHz in the TE03 mode
    No preview · Article · Jan 1988 · International Journal of Electronics

Publication Stats

279 Citations
10.33 Total Impact Points

Institutions

  • 1988-2004
    • Russian Academy of Sciences
      • Institute of Applied Physics
      Moskva, Moscow, Russia
  • 1998
    • National Technical University of Athens
      Athínai, Attica, Greece
  • 1996
    • Karlsruhe Institute of Technology
      • Institut für Technische Physik
      Karlsruhe, Baden-Wuerttemberg, Germany
  • 1990
    • Technische Universität Hamburg-Harburg
      Hamburg, Hamburg, Germany