A W-band gyro-twa based on a CUSP electron gun and helically corrugated waveguide

C. R. Donaldson, W. He, L. Zhang, P. McElhinney, A. D. R. Phelps, A. W. Cross, K. Ronald

Research output: Chapter in Book/Report/Conference proceedingConference contribution book


The latest experimental results of a W-band (75-110 GHz) gyrotron traveling wave amplifier [1] with a helically corrugated waveguide and cusp electron gun is presented. A waveguide with a helical corrugation on its inner surface has ideal dispersive properties which improve the bandwidth of the amplifier whilst maintaining the already good efficiency of operation [2,3]. The large orbit annular electron beam generated by the cusp electron gun [4] is ideal for driving the beam-wave interaction as the beam interacts resonantly with an optimum eigenwave existing in this particular interaction region. The fast-wave interaction is based on the cyclotron resonance maser. When driven by the electron beam of energy 40 keV and current 1.5A, the amplifier was simulated to output 5-10 kW (CW) with a 3 dB frequency bandwidth of 90-100 GHz and saturated gain of 40 dB. The gyro-TWA system includes a 3-layer microwave window, broadband input coupler and quasi-optical mode converter in the form of a corrugated horn. The electron gun has been designed and simulated [5,6] using both MAGIC and Opera and experimentally tested [7] to show the output of a 1.5 A, 40 Kv electron beam with alpha up to 1.56. Experimental results include electron beam profile, current and velocity ration, the microwave power, profile and bandwidth.
Original languageEnglish
Title of host publication2012 Abstracts IEEE International Conference on Plasma Science
Place of PublicationPiscataway, N.J.
Number of pages1
ISBN (Print)978-1-4577-2127-4
Publication statusPublished - 24 Dec 2012


  • cyclotron masers
  • travelling wave amplifiers
  • electron beams
  • cyclotron resonance maser


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