A.B. Pavelyev

Russian Academy of Sciences, Moscow, Moscow, Russia

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Publications (17)7.45 Total impact

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    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.
    Infrared and Millimeter Waves, 2004 and 12th International Conference on Terahertz Electronics, 2004. Conference Digest of the 2004 Joint 29th International Conference on; 01/2004
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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.
    01/2003;
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    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.
    International Journal of Infrared and Millimeter Waves 12/2002; 24(1):1-17. · 0.58 Impact Factor
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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.
    Infrared and Millimeter Waves, 2002. Conference Digest. Twenty Seventh International Conference on; 02/2002
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    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
    Physics and Engineering of Millimeter and Sub-Millimeter Waves, 2001. The Fourth International Kharkov Symposium on; 02/2001
  • 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.
    Radiophysics and Quantum Electronics 07/2000; 43(8):671-674. · 0.96 Impact Factor
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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.
    IEEE Transactions on Plasma Science 07/2000; · 0.87 Impact Factor
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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
    Infrared and Millimeter Waves, 2000. Conference Digest. 2000 25th International Conference on; 02/2000
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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)
    Infrared and Millimeter Waves, 2000. Conference Digest. 2000 25th International Conference on; 02/2000
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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
    Infrared and Millimeter Waves, 2000. Conference Digest. 2000 25th International Conference on; 02/2000
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    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
    Electronics and Radiophysics of Ultra-High Frequencies, 1999. International University Conference Proceedings; 09/1999
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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%
    IEEE Transactions on Plasma Science 07/1998; · 0.87 Impact Factor
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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
    IEEE Transactions on Plasma Science 07/1997; · 0.87 Impact Factor
  • O. Dumbrajs, A. B. 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.
    International Journal of Electronics 01/1997; 82(3). · 0.51 Impact Factor
  • C.T. Iatrou, S. Kern, A.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
    IEEE Transactions on Microwave Theory and Techniques 02/1996; · 2.23 Impact Factor
  • 01/1996;
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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%.
    International Journal of Electronics - INT J ELECTRON. 01/1995; 79(2):227-235.