NIFS-753

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Author(s):

S.Morita, M.Goto, Y.Takeiri, J.Miyazawa, S.Murakami, K.Narihara, M.Osakabe, T.Akiyama, N.Ashikawa, M.Emoto, M.Fujiwara, H.Funaba, P.Goncharov, Y.Hamada, K.Ida, H.Idei, T.Ido, K.Ikeda, S.Inagaki, M.Isobe, K.Itoh, O.Kaneko, K.Kawahata, H.Kawazome, K.Khlopenkov, T.Kobuchi, A.Komori, A.Kostrioukov, S.Kubo, R.Kumazawa, Y.Liang, S.Masuzaki, K.Matsuoka, T.Minami, T.Morisaki, O.Motojima, S.Muto, T.Mutoh, Y.Nagayama, Y.Nakamura, H.Nakanishi, Y.Narushima, K.Nishimura, A.Nishizawa, N.Noda, T.Notake, H.Nozato, S.Ohdachi, K.Ohkubo, N.Ohyabu, Y.Oka, T.Ozaki, B.J.Peterson, A.Sagara, T.Saida, K.Saito, S.Sakakibara, R.Sakamoto, M.Sasao, K.Sato, M.Sato, T.Satow, T.Seki, T.Shimozuma, M.Shoji, S.Sudo, H.Suzuki, N.Takeuchi, N.Tamura, K.Tanaka, K.Toi, T.Tokuzawa, Y.Torii K.Tsumori, T.Uda, K.Y.Watanabe, T.Watari, Y.Xu, H.Yamada, I.Yamada, S.Yamamoto, T.Yamamoto, K.Yamazaki, M.Yokoyama, Y.Yoshimura and M.Yoshinuma

Title:

Study on Ion Temperature Behaviors in Electron and Ion Heating Regimes of ECH, ICRF and NBI Descharges in LHD

Date of publication:

Oct. 2002

Key words:

IAEA, fusion energy conference, Lyon

Abstract:

Ion heating experiments have been carried out in LHD using ECH (82.5, 84.0, 168GHz, leq 1MW), ICRF (38.5MHz, leq 2.7MW) and NBI (H^circ beam: 160keV, leq 8MW). The central ion temperature has been obtained from Doppler broadening of TiXXI (2.61 angstrom) and ArXVII (3.95 angstrom) x-ray lines measured with a newly installed crystal spectrometer. In ECH discharges on-axis heating was recently done with the appearance of high T_e(0) of 6-10keV and high ion temperature of 2.2keV was observed at n_e=0.6x10^13 cm^-3. A clear increment of T_i was also observed with enhancement of the electron-ion energy flow when the ECH pulse was added to the NBI discharge. These results demonstrate the feasibility toward ECH ignition. The clear T_i increment was also observed in ICRF discharges at low density ranges of 0.4- 0.6 x 10^13 cm^-3 with appearance of a new operational range of T_i(0)=2.8keV>T_e(0)=1.9keV. In the low power ICRF heating (1MW), the fraction of bulk ion heating is estimated to be 60% to the total ICRF input power, which means P_i>P_e. Higher T_i(0) up to 3.5keV was obtained for a combined heating of NBI (<4MW) and ICRF (1MW) at density ranges of 0.5-1.5x10^13 cm^-3. The highest T_i(0) of 5keV was recorded in Ne NBI discharges at n_e <1x10^13 cm^-3 with the achievement of T_i(0)>T_e(0), whereas the T_i(0) remained at relatively low values of 2keV in H_2 or He NBI discharges. The main reasons for the high T_i acievement in the Ne descharge are; 1) 30% increment of deposition power, 2) increase in P_i / n_i (11 times, P_i / n_i >> P_e/n_e, P_i<P_e) and 3) increase in au_ei (3 times). The obtained T_i (0) data can be plotted by a smooth function of P_i / n_i.

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