Development of high-power gyrotrons with gradually tapered cavity
- Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China)
In high power gyrotrons, the parasitic modes coupled with the operating mode cannot be avoided in the beam-wave interaction. These parasitic modes will decrease the efficiency of the gyrotrons. The purity of the operating mode affected by different tapers should be carefully studied. The steady-state self-consistent nonlinear theory for gyrotron with gradually tapered cavity is developed in this paper. A steady-state calculation code including 'cold cavity' and 'hot cavity' is designed. By comparison, a time-domain model analysis of gyrotron operation is also studied by particle-in-cell (PIC). It is found that the tapers of gyrotron have different influences on the modes coupling between the operating mode and the parasitic modes. During the study, an example of 94 GHz gyrotron with pure operating mode TE{sub 03} has been designed. The purity of the operating mode in the optimized cavity is up to -77 dB, and in output waveguide of the cavity is up to -76 dB. At the same time, the beam-wave interaction in the designed cavity has been simulated, too. An output power of 120 kW, corresponding to 41.6% efficiency and an oscillation frequency of 94.099 GHz have been achieved with a 50 kV, 6 A helical electron beam at a guiding magnetic field of 3.5485 T. The results show that the power in spurious modes of the optimized cavity may be kept far below than that of the traditional tapered cavity.
- OSTI ID:
- 22072616
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 12 Vol. 19; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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