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Kobayashi, Takayuki; Moriyama, Shinichi; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Igarashi, Koichi; et al.
no journal, ,
In JT-60SA, 7 MW of electron cyclotron heating and current drive will be performed with four units of 110 GHz and five units of 140 GHz electron cyclotron range of frequency (ECRF) systems. Transmission lines will be connected into four upper outer ports where quasi-optical antennas will be installed. Two types of antenna systems are being considered. One is a conventional type rotation antenna and the other is a new concept antenna which can control incident angle by a linearly driven mirror. Those antennas are now being evaluated from the view points of cooling structure, the range of incident angle and beam width. In addition, 1.5 MW for 1 s oscillation was carried out by one gyrotron of JT-60U ECRF system. Moreover, the present 110 GHz gyrotron will be improved which aims at the development of JT-60SA gyrotron. In this presentation, current status of design study for JT-60SA ECRF system and the latest results of the JT-60U ECRF system will be presented.
Kobayashi, Takayuki; Isayama, Akihiko; Terakado, Masayuki; Sato, Fumiaki; Sawahata, Masayuki; Suzuki, Sadaaki; Hiranai, Shinichi; Igarashi, Koichi; Wada, Kenji; Shimono, Mitsugu; et al.
no journal, ,
It is recognized that stabilization of neoclassical tearing mode (NTM) instabilities using power modulated electron cyclotron current drive (ECCD) is effective. Although a modulation frequency of around 5 kHz was required to NTM suppression experiments in JT-60U, the achieved frequency had been limited to 3 kHz due to the slow response time of the high voltage circuit and over-current during charging/discharging. In this study, the anode voltage divider of the system was improved and the capacitance and resistance in the high voltage circuit was optimized resulting in the modulation frequency of over 5 kHz. The robust modulated operation region was also studied with suppressing undesired mode. Moreover, the real-time synchronizing system was developed to control the phase and duty ratio of the modulated ECCD synchronizing with the NTM frequency which varies during ECCD with plasma rotation, and modulated ECCD experiments with NTM suppression was carried out in JT-60U.
Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; et al.
no journal, ,
The electron cyclotron range of frequency (ECRF) system (3 MW 
5s at 110 GHz with 4 gyrotrons) of JT-60U will be upgrade to the system having 9 gyrotrons (7 MW 100s) for JT-60SA (super advanced). As heat removal from the mirrors is essential for a long pulse antenna, a new concept with a mirror driven in the linear motion which eliminates the flexible tube for coolant supply is under development. The design study featuring beam profile calculation showed feasibility of the antenna in the 0.48 m 0.48 m port. The low power rf test with simple mockup antenna has just been begun. Aging of the gyrotron with improved mode converter was started in the end of 2008, aiming at 1 MW, 100s oscillation. Because the current capacity of the present high voltage power supply is not enough to realize 100s oscillation, LHRF power supply having twice larger current capacity is connected to the gyrotron in March 2009. The gyrotron aging will be started soon again.