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Saigusa, Mikio*; Takahashi, Koji; Kashiwa, Yoshinori*; Oishi, Shimpei*; Hoshi, Yuki*; Nakahata, Hiroyuki*; Kasugai, Atsushi; Sakamoto, Keishi; Imai, Tsuyoshi*
Fusion Engineering and Design, 74(1-4), p.473 - 478, 2005/11
Times Cited Count：4 Percentile：30.51(Nuclear Science & Technology)The specification of an electron cyclotron current driving (ECCD) system in International Thermonuclear Experimental Reactor (ITER) demands severe operational conditions for transmission lines and polarizers. For evaluating Ohmic loss of a miter bend type polarizer, the six polarizers were made of chromium copper alloy, installed in miter bends and tested at a frequency of 170GHz, rf power of 441kW and pulse duration of 0.1-6 seconds. The increase in temperature on the back of the grooved mirrors has been measured with thermo couplers during high power rf pulses. The Ohmic loss of grooved mirrors strongly depends on the rotation angle of the polarization plane of the incident waves and the mirror rotation in high power experiments, for example the Ohmic loss distributed from 0.2% to1.6%. The thermal analysis of grooved mirror has been performed with the 3D FEM code: FEVA. The all strange behavior of Ohmic loss of polarizers could be explained, theoretically.
Kashiwa, Yoshinori*; Saigusa, Mikio*; Takahashi, Koji; Oishi, Shimpei*; Hoshi, Yuki*; Kasugai, Atsushi; Sakamoto, Keishi; Imai, Tsuyoshi
Proceedings of 2004 International Symposium on Microwave Science and Its Application to Related Fields (Microwave 2004), p.527 - 530, 2004/07
An electron cyclotron current drive (ECCD) system is, especially, necessary to suppress the neoclassical tearing mode instability in ITER. The polarizers are one of the important components in the ECCD system, to generate optimum polarization for an efficient ECCD. An ohmic loss of the polarizers is evaluated, when 170GHz, high power RF wave taransmits, in oreder to investigate its performance. The maximum temperature increase on the back plate of the deep grooved and the conventinal type were 65
C and 30C, respectively. RF power and pulse were 441kW and 6sec, respectively. The dependence of temperature increase on the plolarizer angle obtained in the experiment agrees with the calculation, qualitatively. It was also found that the significant reduction of ohmic loss on the polarizers was achievable with the optimized rotation angle of the linearly polarized incident wave.
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.
