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Takahashi, Koji; Kobayashi, Noriyuki*; Kasugai, Atsushi; Sakamoto, Keishi
Journal of Physics; Conference Series, 25, p.75 - 83, 2005/00
Recent progress of the development on the ITER equatorial EC launcher components, such as the steering mirrors, its drive system, the waveguide components and the diamond vacuum windows, is reported. Thermmo-mechanical analysis of the recent mirror design shows that maximum temperature increase of 187
C at the reflecting surface and maximum stress of 242MPa at the inner surface of the cooling tube are obtained. In the cyclic test of the spiral tube mock-up, the cyclic number of 1.3
10
is succeeded without failure. In the window development, the fabrication of the Cu-coated edge diamond window and the high power transmission test were done. The Cu-coating on the disk edge can avoid water ingress in the launcher (vessel) under the assumption of the crack formation toward edge. Transmission experiment indicative to 1.2MW, was carried out. Temperature increase of 50C agrees with the calculation. It concludes that the Cu-coated window is capable of MW-level transmission and improves its reliability.
Sakamoto, Keishi; Kasugai, Atsushi; Minami, Ryutaro; Takahashi, Koji; Kobayashi, Noriyuki*
Journal of Physics; Conference Series, 25, p.8 - 12, 2005/00
The present status of ITER gyrotron development of JAERI is reported. Up to now, we demonstrated 100 sec operation at 0.5 MW level power output. On the other hand, some issues were recognized for CW operation, i.e., the beam current decreased as pulse duration expanded. And the large amount of stray RF of 170 GHz exists in the gyrotron. Former, pre-programming control of the heater power of electron gun was introduced to keep the beam current constant. Latter, the inner surface of the radiator was optimized to minimize the diffraction, and loss was reduced by 1/5. Prior to the RF pulse extension, we tried an electron beam test without RF oscillation. As a result, the constant beam current was demonstrated up to 1000 sec.
Fujii, Tsuneyuki; Seki, Masami; Moriyama, Shinichi; Terakado, Masayuki; Shinozaki, Shinichi; Hiranai, Shinichi; Shimono, Mitsugu; Hasegawa, Koichi; Yokokura, Kenji; JT-60 Team
Journal of Physics; Conference Series, 25, p.45 - 50, 2005/00
The JT-60U electron cyclotron range of frequency (ECRF) is utilized to realize high performance plasma. Its output power is 4 MW at 110 GHz. By controlling the anode voltage of the gyrotron used in the JT-60U ECRF heating system, the gyrotoron output can be controlled. Then, the anode voltage controller was developed to modulate the injected power into plasmas. This low cost controller achieved the modulation frequency 12 - 500 Hz at 0.7 MW. This controller also extended the pulse width from 5s to 16 s at 0.5 MW. For these long pulses, temperature rise of the DC break made of Alumina ceramics is estimated. Its maximum temperature becomes 
140 deg. From the analysis of this temperature rise, DC break materials should be changed to low loss materials for the objective pulse width of 30 s. The stabilization of neoclassical tearing mode (NTM) was demonstrated by ECRF heating using the real-time system in which the ECRF beams are injected to the NTM location predicted from ECE measurement every 10 ms.
Takahashi, Koji; Sakamoto, Keishi; Imai, Tsuyoshi; Kasugai, Atsushi; Heidinger, R.*; Thumm, M.*; Moeller, C. P.*
Proceedings of IAEA TM on ECRH Physics and Technology for ITER (CD-ROM), 7 Pages, 2003/00
A front steering (FS) launcher and a remote steering (RS) one have been studied for ITER. In the analysis of a mirror(Cu alloy) for FS launcher, max. temperature of 333C and max. induced stress of 136MPa, less than allowable stress(200MPa), were obtained at the mirror surface under 1MW/1line in CW operation. The efficient transmission (
95%) at -12
12 and 170GHz was performed for both polarizations in the experiments of a square corrugated waveguide for the RS launcher. RF and pressure tests of the diamond window irradiated by neutron were carried under JA/EU(FZK) collaboration. Neutron fluence of the window was 10
n/m
, whereas the estimated annual fluence at the window position is 10
10
n/m. Transmission of 0.48MW-30sec and 0.2MW-132sec were performed. It was successfully demonstrated that the irradiated window withstood 0.4MPa, which was twice higher than the ITER requirement. Diamond windows are applicable for ITER.
Saigusa, Mikio*; Takahashi, Koji; Oishi, Shimpei*; Kashiwa, Yoshitada*; Hoshi, Yuki*; Kobayashi, Yuki*; Kasugai, Atsushi; Sakamoto, Keishi; Imai, Tsuyoshi
Proceedings of IAEA TM on ECRH Physics and Technology for ITER (CD-ROM), 7 Pages, 2003/00
The specified elliptical polarization which is necessary to excite a pure ordinary or extraordinary mode, when rf waves obliquely propagate in plasma, for electron cyclotron current drive(ECCD) can be produced by a grooved mirror polarizer. The Joule loss of deeped groove mirrors has been experimentally investigated at a frequency of 170 GHz. The strange dependence of the Joule loss of groove mirror on the mirror rotation angle was obtained. In addition, maximum loss of 0.8% in regard to the injection rf power to the mirrors was estimated. The calculation code to estimate the Joule loss of grooved mirror is developed for the structure analysis. The dependence of the mirror on its rotation angle can be explained by the calculation results, clearly.
