Characteristics of the JT-60 divertor and limiter plasmas with high power auxiliary heating

JT-60 Team The JT-60 Team, H. Aikawa, N. Akaoka, H. Akasaka, N. Akino, T. Akiyama, T. Ando, K. Annoh, T. Aoyagi, T. Arai, K. Arakawa, M. Araki, M. Azumi, S. Chiba, M. Dairaku, N. Ebisawa, T. Fujii, T. Fukuda, A. Funahashi, H. FurukawaK. Hamamatsu, M. Hanada, M. Hara, K. Haraguchi, H. Hiratsuka, T. Hirayama, S. Hiroki, K. Hiruta, M. Honda, M. Honda, H. Horiike, R. Hosoda, N. Hosogane, T. Iijima, K. Ikeda, Y. Ikeda, T. Imai, T. Inoue, N. Isaji, M. Isaka, S. Ishida, K. Itami, N. Ichige, T. Itoh, T. Kakizaki, A. Kaminaga, T. Katoh, M. Kawai, M. Kawabe, Y. Kawamata, K. Kawasaki, K. Kikuchi, M. Kikuchi, H. Kimura, T. Kimura, H. Kishimoto, S. Kitamura, A. Kitsunezaki, K. Kiyono, N. Kobayashi, K. Kodama, S. Koide, Y. Koide, T. Koike, M. Komata, I. Kondo, S. Konoshima, H. Kubo, S. Kunieda, K. Kurihara, M. Kuriyama, T. Kuroda, M. Kusaka, Y. Kusama, Y. Mabuchi, S. Maehara, K. Maeno, T. Matoba, S. Matsuda, M. Matsukawa, T. Matsukawa, M. Matsuoka, Y. Miura, N. Miya, K. Miyachi, Y. Miyo, M. Mizuno, M. Mori, S. Moriyama, M. Mutoh, M. Nagami, A. Nagashima, K. Nagashima, T. Nagashima, S. Nagaya, O. Naito, H. Nakamura, Y. Nakamura, M. Nemoto, Y. Neyatani, H. Ninomiya, N. Nishino, T. Nishitani, K. Obara, H. Obinata, Y. Ogawa, N. Ogiwara, T. Ohga, Y. Ohara, K. Ohasa, H. Ohara, T. Ohshima, M. Ohkubo, S. Ohsawa, K. Ohta, M. Ohta, M. Ohtaka, Y. Ohuchi, A. Oikawa, H. Okumura, Y. Okumura, K. Omori, S. Omori, Y. Omori, T. Ozeki, M. Saegusa, N. Saitoh, K. Sakamoto, A. Sakasai, S. Sakata, T. Sasajima, K. Satou, M. Satou, M. Satou, A. Sakurai, M. Sawahata, T. Sebata, M. Seimiya, M. Seki, S. Seki, K. Shibanuma, R. Shimada, T. Shimada, K. Shimizu, M. Shimizu, Y. Shimomura, S. Shinozaki, H. Shirai, H. Shirakata, M. Shitomi, K. Suganuma, T. Sugie, T. Sugiyama, H. Sunaoshi, K. Suzuki, M. Suzuki, N. Suzuki, N. Suzuki, S. Suzuki, Y. Suzuki, M. Takahashi, S. Takahashi, T. Takahashi, M. Takasaki, H. Takatsu, H. Takeuchi, A. Takeshita, T. Takizuka, S. Tamura, S. Tanaka, K. Tani, M. Terakado, T. Terakado, K. Tobita, T. Tokutake, T. Totsuka, N. Toyoshima, F. Tsuda, T. Tsugita, S. Tsuji, Y. Tsukahara, M. Tsuneoka, K. Uehara, M. Umehara, Y. Uramoto, H. Usami, K. Ushigusa, K. Usui, J. Yagyu, M. Yamagiwa, M. Yamamoto, T. Yamamoto, O. Yamashita, T. Yamazaki, T. Yasukawa, K. Yokokura, H. Yokomizo, K. Yokoyama, K. Yoshikawa, M. Yoshikawa, H. Yoshida, R. Yoshino, Y. Yoshioka, I. Yonekawa, T. Yoneda, K. Watanabe, M. G. Bell, R. J. Bickerton, W. Engelhardt, Robert James Goldston, E. K. Ilne, J. Kaline, H. W. Kugel, P. L. Mondino, F. X. Soldner, Y. Takase, P. R. Thomas, K. L. Wong

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Essential divertor functions - density and energy control - have been investigated in the JT-60 divertor with metal walls. Neutral pressure in the divertor chamber increases in proportion to n ̄2e and high recycling state for particle exhaust is realized. At ne ≤ 6 × 1019 m-3, wall pumping by the divertor plates is dominant in particle exhaust. However, at n ̄e ≥ 6 × 1019 m-3, particle exhaust by active divertor pumping systems becomes essential. Because of the effectiveness of the divertor, radiation loss in the main plasma is reduced to 5-10% of the absorbed power and impurity concentrations are significantly suppressed at very low level (Zeff = 1.5-2.0). In the experiments with graphite walls, short periods of H-mode phases were found in the outside X-point divertor discharges although improvement in energy confinement is limited to within 10%. In limiter discharges, combination of high vessel temperature (210-300 °C) and low current limiter discharges (1.5 MA) without gas puffing is effective as a wall conditioning in obtaining reproducible high density discharges. The maximum parameters, Ip = 3.2 MA, n ̄e = 1.2 × 1020 m-3, qeff = 2.2 at Bt = 4.8T, a Murakami parameter of 7.5, and a stored energy of 3.1 MJ have been attained. The maximum density is limited by the occurence of the MARFE. During high power neutral beam heating, enhanced carbon influx was observed possibly due to chemical sputtering. The wall pumping by the inner wall is still effective in decreasing the electron density from the high density region of n ̄e ~ 1 × 1020 m-3. An empirical energy confinement scaling of JT-60 has been drawn in terms of an offset linear function as τE = 0.19 I1.9P Pabs + 0.062 a1.8p.

Original languageEnglish (US)
Pages (from-to)93-104
Number of pages12
JournalJournal of Nuclear Materials
Volume162-164
Issue numberC
DOIs
StatePublished - Apr 1 1989

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

Keywords

  • TiC-Mo wall
  • divertor functions
  • graphite wall
  • high current
  • high density plasmas
  • high power heating

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