Initial operation of a 1 MW, 170 GHz gyrotron with an internal mode converter
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center
The authors report the results from initial operation of a high frequency gyrotron suitable for ECH of the International Thermonuclear Experimental Reactor (ITER). The gyrotron is designed to operate in the TE{sub 28,8,1} mode at 170 GHz. The goal is to demonstrate efficient operation at a power level in excess of 1 MW with a Gaussian output beam. The experiment uses a new 7.5 T magnet with a 20 cm bore to provide the cavity magnetic field. The large bore is needed to accommodate the mode converter and mirror transmission line inside the gyrotron that will transform the rf power into a Gaussian beam. The design parameters are listed in a table. This experiment utilizes an 83 kV, 35 A annular electron beam and a tapered cavity. Nonlinear simulations indicate that single mode emission can be achieved with total efficiencies up to 35%. However, the manner in which the gyrotron reaches its final operating parameters is critical. The electrode shapes of the electron gun were chosen so that the beam characteristics would be insensitive to machining errors, and to variations in the operating parameters resulting from misalignment or voltage fluctuations. Gun simulations indicate that the perpendicular velocity spread of the electron gun should not exceed 8%. A peak output power of 1.25 MW has been achieved in TE{sub 27,8,1} mode at 166.6 GHz with 39 A beam current and 95 kV cathode voltage for an efficiency of 35%. Similar results are obtained for TE{sub 28,8,1} and TE{sub 29,8,1} modes.
- OSTI ID:
- 433864
- Report Number(s):
- CONF-960634-; TRN: IM9709%%298
- Resource Relation:
- Conference: 1996 IEEE international conference on plasma science, Boston, MA (United States), 3-5 Jun 1996; Other Information: PBD: 1996; Related Information: Is Part Of IEEE conference record -- Abstracts: 1996 IEEE international conference on plasma science; PB: 324 p.
- Country of Publication:
- United States
- Language:
- English
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