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Kobayashi, Takayuki; Isayama, Akihiko; Suzuki, Sadaaki; Hiranai, Shinichi; Wada, Kenji; Hinata, Jun; Sato, Yoshikatsu; Yokokura, Kenji; Hoshino, Katsumichi; Moriyama, Shinichi
no journal, ,
Design and test of launcher and transmission line for JT-60SA electron cyclotron range of frequency (ECRF) system have been carried out. Spatial profile of temperature rise of 31.75 mm waveguide components, which was used in the previous JT-60, was measured for high-power and long-pulse transmission. It was clarified that improvements of cooling efficiency or change in design is required for achieving 1 MW, 100 s transmission, which is required in JT-60SA. Thus 60.3 mm waveguide components was newly installed. In the preliminary test of the new transmission line, unexpected arcing and increase in vacuum pressure was not observed, and the system worked as expected. As for the launcher, a preliminary layout of the launcher and support was improved in order to keep acceptable distance from systems around the ECRF launcher. Moreover, a mock-up of an improved support structure of the driving shaft using solid lubricants was fabricated in order to improve reliability of the structure.
Takahashi, Koji; Kajiwara, Ken; Oda, Yasuhisa; Kobayashi, Noriyuki*; Oshima, Katsumi; Sakamoto, Keishi
no journal, ,
The mm-wave design of the EL to improve the shielding capability has been investigated and the modification of the mirror position is essential to obtain the effective shielding without degrading the mm-wave transmission capability. The torus diamond window prototype was manufactured and tested. The transmission of 0.74MW/100sec and of 0.52MW/172sec were demonstrated. Loss tangent of 5.54 
10
, which was the lowest value that had ever obtained, was measured. The characteristic temperature increase of the waveguides near and between the miter bends has been measured due to high order modes propagation or/and their modes trapping in the transmission line. The measurement shows that the HE11 mode purity was degraded by 10% and on the other hand, the mode content of LP11 mode was increased by 10% when the displacement of waveguides was 1
1.5mm. This result suggests that the effective cooling of the waveguide or the stiffness support structure for the transmission line component like the miter bend should be considered to minimize the degradation of HE11 mode purity.
Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Yokokura, Kenji; Hoshino, Katsumichi; Shimono, Mitsugu; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; et al.
no journal, ,
Development and design of ECRF system are being carried on toward JT-60SA. In spite of the huge earthquake on March 11th, damage on the system was small, and we restart the gyrotron operation after 2 months of careful inspection and test. The diffraction loss in the gyrotron was kept low and the temperature of the DC break cooling water, which limited the pulse length, was saturated at about half of that before the improvement of the mode convertor. The pulse length reached 31 s at 1 MW and 99 s at 0.3 MW. In JT-60SA, ECRF of about 130-140 GHz would make possible central heating/current drive at BT = 2.25 T. From this point of view, development of dual frequency gyrotron was started. In calculation, oscillation conditions with efficiency of 0.4 were obtained for TE22,8 mode (110 GHz) and TE27,10 mode (137.6 GHz). Fabrication of the gyrotron has just been started. The high power test will be started in the next fiscal year.