Plasma and Fusion Research
Online ISSN : 1880-6821
ISSN-L : 1880-6821
Regular Articles
Optimization of Megawatt 77-GHz Gyrotron Operation for Collective Thomson Scattering in LHD
Shinya OGASAWARAShin KUBOMasaki NISHIURAYoshinori TATEMATSUTeruo SAITOKenji TANAKATakashi SHIMOZUMAYasuo YOSHIMURAHiroe IGAMIHiromi TAKAHASHISatoshi ITORyohei MAKINOSakuji KOBAYASHIYoshinori MIZUNOKohta OKADARyutaro MINAMITsuyoshi KARIYATsuyoshi IMAI
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2013 Volume 8 Pages 2402069

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Abstract

To establish a method for suppressing the spurious radiation that interferes with collective Thomson scattering measurements with less degradation of the main mode output power, the frequency evolution, and the output power of the megawatt 77-GHz gyrotron were measured during operation under optimized parameters. According to a mode competition calculation, the main mode output power may be increased by setting a lower gyrotron anode voltage at a higher magnetic field strength in the gyrotron resonator. Although the output power increased from 300 kW to 530 kW without any spurious radiation when the optimized operational parameters were used, the output power was about 50% of that at a lower magnetic field strength, and thus the output pulse width was limited to 60 ms. When an approach using the optimized operational parameters and a PIN switch was applied, the output power increased to 800 kW without any harmful spurious radiation effect and the pulse width was expanded to 2 s.

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© 2013 by The Japan Society of Plasma Science and Nuclear Fusion Research
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