Recent activities of ITER gyrotron development in QST

ITER Gyrotron: An electron cyclotron heating and current drive system in ITER is designed to inject RF power of 20 MW to control actively plasmas. The RF power is supplied by 24 gyrotrons. QST procures to supply 8 gyrotrons which produce 170 GHz / 1 MW each and 1 equatorial launcher for ITER.
The specification of ITER gyrotron is 170 GHz / 1MW output / 50% efficiency / 3600s pulse duration. The oscillation mode in the cavity is TE31,11 mode to keep marginal heat load on the cavity surface . The internal mode converter was optimized for 170 GHz single frequency operation. The triode electron gun is utilized and the operation of high frequency power modulation up to 5 kHz is achieved by control of anode voltage.
The final design review of the gyrotron was held in 2015 and the gyrotron design was approved for manufacturing. Manufacturing of auxiliary components for gyrotron operation system, for example the super conducting magnets (SCM), started in 2015 and first two sets of SCMs were delivered to QST test stand in the beginning of 2016. In 2016, the first set of two gyrotrons was manufactured in Toshiba Electron Tube & Devices(TETD) and they were delivered to QST Naka Fusion Institute.
The short pulse test of the first ITER gyrotron has started since 2017 April after preparation of test stand. A new anode and body power supply system which has the same configuration with ITER high voltage power supply (HVPS) system was installed into the gyrotron test stand. The new power supply system consists of DC HVPS devices which generate high voltage and HV switch components which control HV injection into gyrotrons. The ITER gyrotron was installed into the test stand with ITER SCM. The conditioning for long pulse operation follows after short pulse test. Preliminary results of shot pulse tests and long pulse conditioning will be presented in the meeting.
Development of multi frequency gyrotron: In QST, the experiment of the multi frequency operation of high power gyrotron was carried out. This gyrotron was designed to produce RF beam of 203 GHz (TE37,13), 170 GHz (TE31,11), 137 GHz (TE25,9) and 104 GHz (TE19,7). These combination of cavity modes for multi frequency operation were selected to adjust the transparent frequency of the output window and to keep the similar radiation angle in the internal mode converter design. This gyrotron was operated with 8T SCM for operation of 203 GHz and its long pulse operation was examined. The output power, the oscillation efficiency and the electric efficiency for 203 GHz, 170 GHz, 137 GHz, and 104 GHz oscillation are 1.0 MW / 30% / 50%, 1.2 MW / 27 % / 43 %, 1.0 MW / 25 % / 40 % and 1.0 MW / 25 % / 38 % at 2 s pulse, respectively. In long pulse experiment of 170 GHz oscillation, the pulse length reached 100 s with 870 kW output power and 1000 s with 500 kW. For other frequency operation, 250 s with 330 kW at 137 GHz, 20 s with 260 kW at 104 GHz, 9.8 s with 590 kW at 203 GHz were achieved.

書誌情報

European Physical Journal

発行日 2017-08

DOI

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DOI

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Ver.1

2023-05-15 22:56:04.511913

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