Experimental studies on NBI and ICRF heated plasmas in the large helical device

K. Kawahata, N. Ohyabu, O. Kaneko, A. Komori, H. Yamada, N. Ashikawa, P. De Vries, M. Emoto, H. Funaba, M. Goto, K. Ida, H. Idei, K. Ikeda, S. Inagaki, N. Inoue, M. Isobe, S. Kado, K. Khlopenkov, S. Kubo, R. KumazawaS. Masuzaki, T. Minami, J. Miyazawa, T. Morisaki, S. Morita, S. Murakami, S. Muto, T. Mutoh, Y. Nagayama, Y. Nakamura, H. Nakanishi, K. Narihara, K. Nishimura, N. Noda, T. Notake, T. Kobuchi, Y. Liang, S. Ohdachi, Y. Oka, M. Osakabe, T. Ozaki, R. O. Pavlichenko, B. J. Peterson, A. Sagara, K. Saito, S. Sakakibara, R. Sakamoto, H. Sasao, M. Sasao, K. Sato, M. Sato, T. Seki, T. Shimozuma, M. Shoji, H. Suzuki, M. Takechi, Y. Takeiri, N. Tamura, K. Tanaka, K. Toi, T. Tokuzawa, Y. Torii, K. Tsumori, I. Yamada, S. Yamaguchi, S. Yamamoto, M. Yokoyama, Y. Yoshimura, K. Y. Watanabe, T. Watari, K. Itoh, K. Matsuoka, K. Ohkubo, I. Ohtake, S. Satoh, T. Satow, S. Sudo, S. Tanahashi, K. Yamazaki, Y. Hamada, O. Motojima, M. Fujiwara

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Abstract

In the Large Helical Device (LHD), upgrading of the key hardware system since the last EPS conference has led to (1) higher Te (Te(0) = 4.4 keV at 〈ne〉 = 5.3×1018 m-3 and Pabs = 1.8 MW); (2) higher confinement (τE = 0.3 s, Te(0) = 1.1 keV at 〈ne〉 = 6.5×1019 m-3 and Pabs = 2.0 MW); (3) higher stored energy Wpdia = 880 kJ; and (4) the highest β value in helical devices (2.4% at B = 1.3 T). The energy confinement was systematically higher than that predicted by the International Stellarator Scaling 95 up to a factor of 1.6. Ion cyclotron range of frequencies (ICRF) power up to 1.3 MW was reliably injected into the plasma without significant impurity contamination and a plasma with stored energy of 200 kJ was sustained for 5 s by ICRF alone. Long pulse discharges greater than 1 min in duration have been successfully achieved with ICRF power alone and with neutral beam injection (NBI) power alone. With NBI heating an 80 s discharge was achieved with a heating power of 0.5 MW at 2.75 T. The electron density was maintained at around 1.6×1019 m-3 by controlled gas puffing. The central electron and ion temperatures were kept around 1.5 keV. With ICRF heating, a similar long pulse discharge was achieved for 68 s with a heating power of 0.85 MW. The sustained plasma parameters are: Wp approximately 110 kJ, Te(0) approximately Ti(0) = 2.0 keV and 〈ne〉 = 1.0×1019 m-3. During these discharges, no increase in radiation power has been observed.

Original languageEnglish
Pages (from-to)B51-B60
JournalPlasma Physics and Controlled Fusion
Volume42
Issue number12 SUPPL. B
DOIs
Publication statusPublished - Dec 2000
Event27th European Physical Society Conference on Controlled Fusion and Plasma Physics - Budapest, Hung
Duration: Jun 12 2000Jun 16 2000

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All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

Cite this

Kawahata, K., Ohyabu, N., Kaneko, O., Komori, A., Yamada, H., Ashikawa, N., ... Fujiwara, M. (2000). Experimental studies on NBI and ICRF heated plasmas in the large helical device. Plasma Physics and Controlled Fusion, 42(12 SUPPL. B), B51-B60. https://doi.org/10.1088/0741-3335/42/12B/305