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Frequency-Tunable CW Gyro-BWO with a
Helically |
Rippled Operating Waveguide
G.G.
Denisov1), S.V. Samsonov1), V.L. Bratman1), A.A. Bogdashov1), M.Yu. Glyavin1),
A.G. Luchinin1), V.K.
Lygin1), M. Thumm2)
1) Institute of Applied Physics, Russian Academy of
Sciences
603155
Nizhny Novgorod, Russia
2) Forschungszentrum Karlsruhe,
Institut fuer Hochleistungsimpuls- und Mikrowellentechnik
D-76021 Karlsruhe, Germany
Abstract
The gyrotron backward-wave
oscillator (gyro-BWO) is known as a source of frequency-tunable high-power
coherent radiation, which is attractive for a number of applications. This was
the motivation to develop a CW tunable gyro-BWO with a power of several
kilowatts at the frequency of about 24 GHz.
The gyro-BWO exploits a DC oil-cooled magnet with
magnetic field up to 0.5 T and utilizes a weakly-relativistic
(20 keV) electron beam produced by a magnetron injection gun. A stable
generation at the second cyclotron harmonic with a maximum power of 7 kW
and interaction efficiency of 15% at the frequency of 24.7 GHz was
achieved. Smooth oscillation frequency tuning by varying the magnetic field was
measured to be as wide as 5% at half-power level. The use of a depressed collector
provided an efficiency increase up to 23% and an opportunity for a reduction of
the main power supply voltage down to 10 kV