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ABSTRACT: A relativistic backward wave oscillator for the 10-GHz range with the oscillation frequency tuned within about 5% by changing
the accelerating voltage from 600 to 350 kV has been developed. Discrete variations in the voltage and the corresponding frequency
tuning from pulse to pulse is rapidly performed by changing the anode-cathode distance in the vacuum diode without breaking
vacuum in the working volume. During this, the electron beam power remains almost constant, while the output microwave power
varies within 0.4–0.8 GW. The introduction of a dielectric cylinder into the accelerating gap provides a smooth voltage drop
from 600 to 350 kV with the corresponding frequency tuning during a 20-ns pulse.
Technical Physics Letters 04/2012; 36(2):140-143. · 0.56 Impact Factor
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ABSTRACT: The effect of passive compression of frequency-modulated pulses in dispersive media is used to raise the microwave radiation
peak power to a multigigawatt level. A waveguide with a helically corrugated surface is applied as a dispersive medium, and
a relativistic 3-cm backward-wave oscillator with an accelerating voltage decaying within the pulse duration serves as a source
of frequency-modulated pulses. The compression of pulses to an FWHM of 2.2 ns attended by a rise in the peak power by a factor
of 4.5 (to 3.2 GW) is demonstrated with a SINUS-6 accelerator.
Technical Physics 04/2012; 56(2):269-273. · 0.50 Impact Factor
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L Zhang,
A W Cross,
W He,
C G Whyte,
M McStravick,
A R Young,
K Ronald,
C W Robertson,
A D R Phelps, S V Samsonov,
S V Mishakin,
V L Bratman,
G G Denisov,
N G Kolganov
Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2012 37th International Conference on; 01/2012
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Physics of Plasmas 11/2010; 17. · 2.15 Impact Factor
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M. McStravick,
K. Ronald, S.V. Samsonov,
S.V. Mishakin,
W. He,
G.G. Denisov,
C.G. Whyte,
A.R. Young,
V.L. Bratman,
C.W. Robertson,
A.W. Cross,
N.G. Kolganov,
A.D.R. Phelps,
P. MacInnes
[show abstract]
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ABSTRACT: The results of 3-fold helically corrugated waveguide microwave pulse compression experiments are presented. A pulse of 80 ns duration having a power of 5.6 kW is compressed into a 140 kW peak power pulse of 1.5 ns duration. To enhance the power capabilities of the microwave pulse compressor a larger diameter 5fold helical waveguide structure was studied; the eigenwave dispersion is discussed using numerical, analytical, and experimental techniques.
Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2010 35th International Conference on; 10/2010
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Journal of Applied Physics 09/2010; · 2.17 Impact Factor
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ABSTRACT: Simultaneous generation at the second and fourth cyclotron harmonics has been obtained from a single-cavity gyromultiplier. Output power of the short-wavelength radiation amounts to 100 W at a frequency of 75 GHz. The proposed scheme seems to be promising for the terahertz frequency range.
Infrared, Millimeter, and Terahertz Waves, 2009. IRMMW-THz 2009. 34th International Conference on; 10/2009
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Yu.V. Bykov,
G.G. Denisov,
A.G. Eremeev,
F.A. Flat,
M.Yu. Glyavin,
A.M. Gorbachev,
G.I. Kalynova,
V.V. Kholoptsev,
E.A. Kopelovich,
A.G. Luchinin,
I.V. Plotnikov,
M.V. Morozkin, S.V. Samsonov,
A.L. Vikharev
[show abstract]
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ABSTRACT: Second harmonic 24-28 GHz CW gyrotrons and series of gyrotron based setups for material processing and Electron Cyclotron Resonance Ion Sources (ECRIS) has been developed at IAP RAS. The possibility of significant output efficiency enhancement due to energy recovery for gyrotrons operating at cyclotron harmonic is demonstrated. The efficiency of 60% at 6 kW output power level at second harmonic 24 GHz gyrotron has been obtained by magnetic field profile optimization and single-stage energy recovery of the spent electron beam. It is shown, that the energy to sintering process can be significantly reduced (1.5-2 times) by simultaneous control of gyrotron voltage and solenoid current. Different varieties of broadband frequency gyro devices - multi-frequency or fast-swept in time operation - are under investigation for ECRIS. The double-frequency CW 10 kW second harmonic gyrotron with 2% fast frequency and a frequency-tunable gyro-BWO operating at center frequency of 60 GHz with CW output power about 10 kW are presented.
Infrared, Millimeter, and Terahertz Waves, 2009. IRMMW-THz 2009. 34th International Conference on; 10/2009
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[show abstract]
[hide abstract]
ABSTRACT: Simultaneous generation at the second and fourth cyclotron harmonics has been obtained from a single-cavity self-excited gyromultiplier. Output power of the short-wavelength radiation amounts to 100 W at a frequency of 75 GHz. The proposed scheme seems to be promising for the terahertz frequency range.
Physics of Plasmas 07/2009; 16(7):070701-070701-3. · 2.15 Impact Factor
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M. McStravick,
A.W. Cross,
W. He,
K. Ronald,
C.G. Whyte,
A.D.R. Phelps,
I.V. Konoplev,
P. McInnes,
A.R. Young, S.V. Samsonov,
S.V. Mishakin,
G.G. Denisov,
V.L. Bratman,
N.G. Kolganov
[show abstract]
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ABSTRACT: X-band passive microwave pulse compression is an interesting area of research in vacuum electronics. Applications include radar technology, plasma diagnostics etc. The scientific study of producing high-power nanosecond microwave pulses, using passive sweep-frequency compression, was undertaken. Two novel helically corrugated waveguides were investigated; 3-fold and 5-fold, respectively. The 3-fold structure couples a TE<sub>1.1</sub> travelling wave with a near cut-off TE<sub>2.1</sub> wave producing a region far from cut-off with a large change in group velocity as a function of frequency. A 2.08 metre long copper helical waveguide was used to compress a 80 ns, 5.5 kW frequency-swept pulse from a high power TWT (TMD PTC6321), driven by an arbitrary waveform generator and vector signal generator, to a 1.5 ns, 135 kW pulse containing -75% of the energy of the input pulse. To enhance the power capabilities of the microwave pulse compressor a more overmoded larger diameter 5-fold helical waveguide structure which adiabatically couples a TE<sub>3.1</sub> traveling wave and a near cut-off TE<sub>2.2</sub> wave was studied. Analysis of the dispersion characteristics carried out using CST MWS will be presented.
Vacuum Electronics Conference, 2009. IVEC '09. IEEE International; 05/2009
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ABSTRACT: Two kinds of gyro-devices are considered: gyrotrons for material processing and tunable microwave devices for Electron Cyclotron Ion Sources. The possibility of the significant output efficiency enhancement due to energy recovery for the gyrotrons operating at cyclotron harmonics was demonstrated. The second-harmonic 24 GHz gyrotron for technology application with output efficiency of 60% was developed and tested at IAP RAS. Record efficiency was obtained by optimizing the profile of the magnetic field and using the energy recovery for the spent electron beam. Different varieties of gyro-devices providing broadband radiation (multi-frequency or fast-swept in time) with CW or average power of order of 10-15 kW and the center frequency within the range of 24-60 GHz are also discussed.
Vacuum Electronics Conference, 2009. IVEC '09. IEEE International; 05/2009
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ABSTRACT: For 3d waveguiding system calculations we used the Electric Field Integral Equation (EFIE) model, applied to infinitely thin,
perfectly conducting waveguide surfaces. The solution represents induced current, from which the field in the device is obtained.
With the help of this method an asymmetric mode converter TE01-TE11 was simulated and optimized for maximum efficiency. We
have also studied a helically corrugated structure, which is used in pulse compressors, and analyzed the structures dispersion
curves and compared it with measurement results.
Journal of infrared, millimeter and terahertz waves 03/2009; 30(4):319-327. · 0.74 Impact Factor
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ABSTRACT: Progress on the study of a 3<sup>rd</sup>-harmonic large orbit gyrotron with the radiation frequency of 1 THz and a prototype of a promising gyro-multiplier at the 4<sup>th</sup> harmonic are presented.
Infrared, Millimeter and Terahertz Waves, 2008. IRMMW-THz 2008. 33rd International Conference on; 10/2008
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M. McStravick, S.V. Samsonov,
A.W. Cross,
G.G. Denisov,
W. He,
P. MacInnes,
A.D.R. Phelps,
V.L. Bratman,
K. Ronald,
S. Mishakin,
I.V. Konoplev,
G. Burt,
A.R. Young,
C.G. Whyte
[show abstract]
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ABSTRACT: Waveguide with a helical corrugation of the inner surface has the desirable properties of optimised dispersion, operation far from cut-off and high breakdown field strength which make it an excellent medium for passive pulse compression. New compression measurements at both milli-watt and kilowatt powers using an optimised frequency modulation of the input pulse will be presented and discussed.
Infrared, Millimeter and Terahertz Waves, 2008. IRMMW-THz 2008. 33rd International Conference on; 10/2008
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ABSTRACT: We use the well-known method of analysis of oversized electrodynamic systems, which is based on numerical solution of the
integral equation for the surface current and is employed to calculate diffraction of an electromagnetic field by arbitrary
conducting surfaces, for calculation of the characteristics of waveguide structures. In contrast to the finite-difference
algorithms for straightforward solution of the Maxwell equations, which are dealt with the field components in the calculation
space divided into cells with small sizes (compared with the wavelength), the desired quantity in this method is the current
on the conducting surface bounding the structure. This reduces the required RAM capacity and speeds up calculations by several
orders of magnitude in the case of oversized systems. In this work, the integral equation method is realized in the form of
a computer code and is used to calculate three-dimensional multimode waveguide systems. The calculation results are compared
with the results of perturbation theory and the experimental data.
Radiophysics and Quantum Electronics 01/2008; 51(9):671-680. · 0.71 Impact Factor
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ABSTRACT: Recent results on low-relativistic second-harmonic gyro-devices using a microwave system in the form of a helically corrugated waveguide are presented. New Ka-band gyro-TWT is designed to operate with peak power of 100-120 kW, average power up to 10 kW and frequency bandwidth of about 10%. In the first experimental test a peak power of 130 kW, efficiency of 22-24% and bandwidth at least 2 GHz were achieved for 70-kV electron beam with pulse length up to 100 mus and repetition frequency up to 5 Hz. Frequency-tunable gyro-BWOs, attractive for some technological applications, enable CW output power of several kW at 24 GHz with smooth frequency tuning of 4-6%.
Infrared and Millimeter Waves, 2007 and the 2007 15th International Conference on Terahertz Electronics. IRMMW-THz. Joint 32nd International Conference on; 10/2007
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ABSTRACT: The theoretical analysis and proof-of-principle experiments at kilowatt power levels showed that X-band radiation of 50-70 ns duration with 3-5% frequency modulation can be compressed into 1-3 ns pulses having 10-30 times higher peak power. This region of operating parameters in conjunction with low reflection and high RF electric strength makes the helical waveguide compressor attractive for increasing the peak power from relativistic non-resonant electron devices such as BWOs and TWTs up to the multigigawatt level.
Vacuum Electronics Conference, 2007. IVEC '07. IEEE International; 06/2007
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ABSTRACT: We review the studies of gyrotron-type microwave devices whose electrodynamic system has the form of an oversized metal waveguide
with a helically corrugated internal surface. For certain parameters, such a corrugation changes radically the waveguide dispersion
ensuring an almost constant group velocity of the eigenmode for a small (close to zero) longitudinal wave number in a wide
frequency band. The use of “helical” waveguides along with electron optical systems which form near-axis electron beams makes
it possible to create high-efficiency amplifiers based on gyro-traveling-wave tubes (gyro-TWTs) with a wide instantaneous
frequency band of amplification and gyro-backward-wave oscillators (gyro-BWOs) with continuous wideband tuning of the oscillation
frequency. The studied devices are superior to the well-studied microwave sources of this type (gyroklystrons and gyrotrons)
in frequency band, by more than an order of magnitude, and are not inferior to them in efficiency even for a wide spread of
electron velocities.
Radiophysics and Quantum Electronics 01/2007; 50(2):95-107. · 0.71 Impact Factor
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[show abstract]
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ABSTRACT: We show theoretically that the use of a circular oversized waveguide with a helically corrugated internal surface as a dispersive
medium ensures efficient compression of frequency-modulated microwave pulses up to peak powers of about 10 GW. According to
the calculations, a pulse with the required frequency modulation can be obtained in a relativistic backward-wave oscillator
operated in the 3-cm wavelength range and producing an output power of hundreds of megawatts. In a demonstration experiment,
a 80-ns pulse of kilowatt power with frequency modulation in a 5% band was compressed to a 1.5-ns pulse with a 25-fold power
amplification.
Radiophysics and Quantum Electronics 12/2006; 50(1):36-48. · 0.71 Impact Factor
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ABSTRACT: We propose a realization of the iterative method for synthesis of waveguide-mode converters in the case of a two-dimensional
deformation of the waveguide. Examples of the converters calculated using this method are presented. The method allows finding
essentially new solutions for the problems of development of mode converters.
Radiophysics and Quantum Electronics 11/2006; 49(12):961-967. · 0.71 Impact Factor
