Gyro-BWO experiments using a helical interaction waveguide

W. He, K. Ronald, A.R. Young, A.W. Cross, A.D.R. Phelps, C.G. Whyte, E.G. Rafferty, J. Thomson, C.W. Robertson, David Speirs, S.V. Samsonov, V.L. Bratman, G.G. Denisov

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79 Citations (Scopus)


A helically corrugated waveguide was used for a gyrotron backward-wave oscillator (gyro-BWO) experiment. A thermionic cathode was used to produce an electron beam of 90-215 keV in energy, 2-3 A in current, and pitch alpha of up to 1.6. The oscillator achieved high-efficiency frequency-tunable operation. At a fixed beam voltage of 185 kV and a current of 2 A, the output frequency was tuned by adjusting the magnetic field in the interaction cavity. A maximum power of 62 kW and a 3-dB frequency-tuning band of 8.0-9.5 GHz (17% relative tuning range) with a maximum electronic efficiency of 16.5% were measured. In addition, the interaction frequency could be tuned by varying the electron beam energy. At a fixed cavity magnetic field of 0.195 T, the output frequency and power from the gyro-BWO were measured as a function of tuning electron beam energy while the beam current was maintained at 2.5 A. A 3-dB relative frequency tuning range of 8% was measured when the electron beam voltage was changed from 215 to 110 kV.
Original languageEnglish
Pages (from-to)839-844
Number of pages5
JournalIEEE Transactions on Electron Devices
Issue number5
Publication statusPublished - May 2005


  • backward wave oscillators
  • gyrotrons
  • helical waveguides
  • thermionic cathodes
  • plasma
  • cyclotron-resonance maser
  • high-power microwave devices


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