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1. Recent results of LH experiments on the JT-60 tokamak

Author

N Akaoka, H Akasaka, M Akiba, N Akino, T Ando, K Annou, T Aoyagi, T Arai, K Arakawa, M Araki, M Azumi, S Chiba, M Dairaku, N Ebisawa, T Fujii, T Fukuda, A Funahashi, H Furukawa, H Gunji, K Hamamatsu, M Hanada, M Hara, K Haraguchi, H Hiratsuka, T Hirayama, S Hiroki, K Hiruta, M Honda, H Horiike, N Hosogane, Y Iida, T Iijima, K Ikeda, Y Ikeda, T Imai, T Inoue, N Isaji, M Isaka, N Isei, S Ishida, K Itami, N Itige, T Ito, T Kakizaki, Y Kamada, A Kaminaga, T Kaneko, M Kawai, M Kawabe, Y Kawamata, Y Kawano, K Kikuchi, M Kikuchi, H Kimura, T Kimura, H Kishimoto, S Kitamura, K Kiyono, K Kodama, Y Koide, T Koide, T Kobayashi, M Komata, I Kondo, T Kondo, S Konoshima, H Kubo, S Kunieda, K Kurihara, M Kuriyama, M Kusaka, Y Kusama, T Kushima, M Maeno, T Matoba, S Matsuda, M Matsukawa, M Matsuoka, Y Matsuzaki, Y Miura, N Miya, K Miyachi, K Miyake, Y Miyo, M Mizuno, K Mogaki, S Moriyama, Y Murakami, M Muto, M Nagami, A Nagashima, K Nagashima, T Nagashima, S Nagaya, K Nagayama, O Naito, H Nakamura, T Nagafuji, H Nemoto, M Nemoto, Y Neyatani, H Ninomiya, N Nishino, T Nishitani, H Nobusaka, H Nomata, A Oikawa, K Obara, K Odajima, N Ogiwara, T Ohga, Y Ohara, H Oohara, T Ohshima, K Ohta, M Ohta, S Ohuchi, Y Ohuchi, H Okumura, K Omori, S Omori, Y Omori, T Ozeki, M Saegusa, N Saitoh, A Sakasai, S Sakata, T Sakuma, T Sasajima, K Satou, M Satou, M Sawahata, M Seimiya, M Seki, S Seki, K Shibanuma, M Shimada, K Shimizu, M Shimizu, Y Shimomura, S Shinozaki, H Shirai, H Shirakata, M Shitomi, K Suganuma, T Sugawara, T Sugie, H Sunaoshi, M Suzuki, N Suzuki, S Suzuki, H Tachibana, M Takahashi, S Takahashi, T Takahashi, M Takasaki, H Takatsu, H Takeuchi, A Takeshita, T Takizuka, S Tamura, S Tanaka, T Tanaka, Y Tanaka, T Tani, M Terakado, T Terakado, K Tobita, T Totsuka, N Toyoshima, T Tsugita, S Tsuji, Y Tsukahara, M Tsuneoka, K Uehara, Y Uramoto, H Usami, K Ushigusa, K Usui, J Yagyu, K Yamagishi, M Yamagiwa, M Yamamoto, O Yamashita, T Yamazaki, K Yokokura, K Yokoyama, H Yoshida, Z Yoshida, R Yoshino, Y Yoshioka, I Yonekawa, and K Watanabe

Subjects
Materials science, Tokamak, Divertor, Atmospheric-pressure plasma, Plasma, Condensed Matter Physics, Instability, Ion, law.invention, Nuclear Energy and Engineering, law, Atomic physics, JT-60, Electric current
Abstract

Recent lower hybrid current drive (LHCD), and heating (LHH) experiments on JT-60 are reported. The current drive product of neRpIRF approximately 12.5*1019 m-2 MA was achieved at the LH power of approximately 4.5 MW, and the CD efficiency, the energy confinement, the global power balance and the heat load on divertor plates were investigated in high power LHCD plasmas. Nearly steady state H-mode discharges were found during LHCD with two different frequency injections. Sawtooth suppression in NB heated plasmas by LHCD have shown an improvement in confinement near the plasma center. Parametric instabilities in LH heating experiments were significantly reduced by increasing the plasma current, and the stored energy increased linearly with heating power of up to approximately 9 MW at ne approximately 7*1019 m-3 and Ip=2.75 MA. Parametric instabilities near the plasma edge in the ion heating regime were also reduced in peaked density plasmas produced by pellet injection and LH waves increased the central plasma pressure at ne(0) > 1.4*1020 m-3.

Published
1990

2. Recent results in JT-60 experiments

Author

M Nagami, I Aoki, N Akaoka, H Akasaka, M Akiba, N Akino, T Ando, K Annou, T Aoyagi, T Arai, K Arakawa, M Araki, M Azumi, S Chiba, M Dairaku, N Ebisawa, T Fujii, T Fukuda, A Funahashi, H Furukawa, H Gunji, K Hamamatsu, M Hanada, M Hara, K Haraguchi, H Hiratsuka, T Hirayama, S Hiroki, K Hiruta, M Honda, H Horiike, R Hosada, N Hosogane, K Iida, Y Iida, T Iijima, K Ikeda, Y Ikeda, T Imai, T Inoue, N Isaji, M Isaka, S Ishida, K Itami, N Itige, T Ito, T Kakizaki, Y Kamada, A Kaminaga, T Kaneko, T Kato, M Kawai, M Kawabe, Y Kawamata, Y Kawano, K Kawasaki, K Kikuchi, M Kikuchi, H Kimura, T Kimura, H Kishimoto, S Kitamura, K Kiyono, N Kobayashi, K Kodama, Y Kurihata, Y Koide, T Koike, M Komata, I Kondo, S Konoshima, H Kubo, S Kunieda, K Kurihara, M Kuriyama, M Kusaka, Y Kusama, T Kushima, Y Mabuti, S Maehara, K Maeno, T Matoba, S Matsuda, M Matsukawa, T Matsukawa, M Matsuoka, Y Matsuzaki, Y Miura, N Miya, K Miyachi, Y Miyo, M Mizuno, K Mogaki, S Moriyama, Y Murakami, M Muto, K Nagase, A Nagashima, K Nagashima, T Nagashima, S Nagaya, O Naito, H Nakamura, H Nemoto, M Nemoto, Y Neyatani, H Ninomiya, N Nishino, T Nishitani, H Nobusaka, H Nomata, K Obara, K Odajima, Y Ogawa, N Ogiwara, T Ohga, Y Ohara, H Oohara, T Ohshima, K Ohta, M Ohta, S Ohuchi, Y Ohuchi, H Okumura, Y Okumura, K Omori, S Omori, Y Omori, T Ozeki, M Saegusa, N Saitoh, A Sakasai, S Sakata, T Sasajima, K Sato, M Sato, M Sawahata, T Sebata, M Seimiya, M Seki, S Seki, K Shibanuma, M Shimada, R Shimada, K Shimizu, M Shimizu, Y Shimomura, S Shinozaki, H Shirai, H Shirakata, M Shitomi, K Suganuma, T Sugawara, T Sugie, H Sunaoshi, M Suzuki, N Suzuki, S Suzuki, H Tachibana, M Takahashi, S Takahashi, T Takahashi, M Takasaki, H Takatsu, H Takeuchi, A Takeshita, T Takizuka, S Tamura, S Tanaka, T Tanaka, Y Tanaka, K Tani, M Terakado, T Terakado, K Tobita, T Totsuka, N Toyoshima, F Tsuda, T Tsugita, S Tsuji, Y Tsukahara, M Tsuneoka, K Uehara, Y Uramoto, H Usami, K Ushigusa, K Usui, J Yagyu, M Yamagiwa, M Yamamoto, O Yamashita, T Yamazaki, K Yokokura, K Yokoyama, K Yoshikawa, H Yoshida, R Yoshino, Y Yoshioka, I Yonekawa, T Yoneda, and K Watanabe

Subjects
Electron density, Materials science, Nuclear Energy and Engineering, Radiative cooling, Divertor, Electron, Sawtooth wave, Plasma, Atomic physics, Condensed Matter Physics, Pressure gradient, Neutral beam injection
Abstract

Emphases in JT-60 experiments are placed on (1) lower-hybrid (LH) current drive characteristics with a multi-junction type launcher, and (2) the confinement study with combination of neutral beam injection LH current drive and pellet injection. The new multi-junction LH launcher provides a sharp N/sub /// spectrum with high directivity for N/sub ///=1-3.4. The current drive efficiency and the radial distribution of high energy electron production show clear correlation with injected N/sub ///: the current drive efficiency has the maximum at low N/sub ///( approximately 1.3) while flattening of plasma current is more effective in large N/sub ///. A broad radial distribution of high energy electron current and approximately 30% reduction in sawtooth inversion radius were obtained by high N/sub /// ( approximately 2.5) LH injection. To fully suppress the sawtooth activity, low N/sub /// ( approximately 1.3) injection was found to be more effective. Improved energy confinement has been obtained with hydrogen pellet injection. Energy confinement time was enhanced up to 40% relative to usual gas fuelled discharges. The discharge has a strongly peaked electron density profile with ne(0)/(ne) approximately 5 and ne(0) approximately 2.0*1020 m-3. The improved discharges are characterized by a strongly peaked pressure profile within the q=1 magnetic surface, and degrades when a large sawtooth recovers or the pressure gradient may reach a critical value. When large (3 mm, 4 mm) and fast (2.2 km/s) pellets were injected, 30% energy confinement improvement was obtained even during the NB heating of 14 MW. Further investigations of IDC characteristics have been made. The oxygen impurity lines from the main plasma and the main radiative loss drop first. Then the plasma stored energy starts to rise. The particle recycling is reduced around the main plasma, and is localized in the neighborhood of the X-point with a time lag of approximately 0.2 sec. Eventually the discharge shows a significant remote radiative cooling power at the divertor region.

Published
1989

3. Initial experiments in JT-60

Author

T Abe, H Aikawa, N Akaoka, H Akasaka, N Akino, T Akiyama, T Ando, K Anno, T Aoyagi, T Arai, K Arakawa, M Azumi, T Fukuda, H Furukawa, K Hammamatsu, T Haraguchi, K Hayashi, H Hiratsuka, T Hirayama, S Hiroki, K Hiruta, N Hitomi, R Hosoda, N Hosogane, H Ichige, S Iida, T Iijima, Y Ikeda, N Isaji, M Isaka, M Ishihara, Y Itoh, M Kaneko, Y Kawamata, K Kawasaki, M Kikuchi, T Kimura, H Kishimoto, K Kitahara, A Kitsunezaki, K Kodama, Y Koide, T Koike, I Kondo, S Konoshima, H Kubo, S Kunieda, K Kurihara, T Kuroda, H Maeda, M Maeno, M Matsukawa, T Matsukawa, M Matsuo, N Miya, K Miyachi, Y Miyo, M Mizuno, Y Murakami, M Mutoh, M Nagami, A Nagashima, K Nagashima, S Nagaya, H Nakamura, Y Nakamura, M Nemoto, Y Neyatani, S Niikura, H Ninomiya, T Nishitani, T Nishiyama, H Nomata, S Noshiroya, N Ogiwara, K Ohasa, M Ohkubo, K Ohmori, S Ohmori, Y Ohmori, Y Ohsato, T Ohshima, M Ohta, K Otsu, A Oikawa, T Ozeki, A Sakasai, S Sakata, M Sato, M Seimiya, S Seki, M Shiho, M Shitomi, R Shimada, K Shimizu, M Shimizu, Y Shimomura, S Shinozaki, H Shirai, T Sugie, H Sunaoshi, K Suzuki, M Suzuki, S Suzuki, Y Suzuki, S Tahira, M Takahashi, S Takahashi, T Takahashi, H Takatsu, Y Takayasu, S Takeda, H Takeuchi, T Takizuka, S Tamura, E Tanaka, T Tanaka, K Tani, T Terakado, K Tobita, T Tokutake, T Totsuka, N Toyoshima, T Tsugita, S Tsuji, Y Tsukahara, M Tsuneoka, K Ujiie, H Urakawa, Y Uramoto, K Ushigusa, J Yagyu, K Yamada, M Yamamoto, O Yamashita, Y Yamashita, K Yano, H Yokomizo, I Yonekawa, H Yoshida, M Yoshikawa, and R Yoshino

Subjects
Materials science, Nuclear Energy and Engineering, Divertor, Limiter, High density, Plasma, JT-60, Atomic physics, Condensed Matter Physics, Joule heating, Ohmic contact, Plasma current
Abstract

Initial ohmic heating experiments in JT-60 were performed for a three month period of April-June 1985. A maximum plasma current of 1.6 MA was obtained for both divertor and limiter discharges. Low-q discharges of qeff=2.5 and high density discharges of 4.8*1019 m-3 in line-averaged density were obtained in the divertor configuration. In divertor discharges radiated loss from the main plasma can be kept at 20-30% of the ohmic input.

Published
1986

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

Author

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 Furukawa, K Hamamatsu, M Hanada, M Hara, K Haraguchi, H Hiratsuka, T Hirayama, S Hiroki, K Hiruta, 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, 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, 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, R.J Goldston, E.K Ilne, J Kaline, H.W Kugel, P.L Mondino, F.X Soldner, Y Takase, P.R Thomas, and K.L Wong

Subjects
Nuclear and High Energy Physics, Electron density, Current limiting, Materials science, Nuclear Energy and Engineering, Sputtering, Divertor, Limiter, Maximum density, General Materials Science, Plasma, JT-60, Atomic physics
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 n2e and high recycling state for particle exhaust is realized. At ne ≤ 6 × 1019m−3, wall pumping by the divertor plates is dominant in particle exhaust. However, at ne ≥ 6 × 1019m−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, ne = 1.2 × 1020m−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 ne ~ 1 × 1020m−3. An empirical energy confinement scaling of JT-60 has been drawn in terms of an offset linear function as τE = 0.19 I1.9PPabs + 0.062 a1.8p

Published
1989

5. High power heating results on JT-60

Author

M Akiba, 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 Furukawa, K Hamamatsu, M Hanada, M Hara, K Haraguchi, H Hiratsuka, T Hirayama, S Hiroki, K Hiruta, M Honda, H Horiike, R Hosoda, N Hosogane, T Iijima, Y Ikeda, K 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 Kioke, 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 Mori, S Moriyama, M Mutoh, M Nagami, A Nagashima, K Nagashima, T Nagashima, S Nagaya, O Naitoh, 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 Oohara, 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, 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, S Suzuki, Y Suzuki, M Takahashi, S Takahashi, T Takahashi, M Takasaki, H Takatsu, H Takeuchi, A Takeshita, T Takizuka, S Tamura, S Tanaka, T Tanaka, K Tani, M Terakado, T Terakado, K Tobita, T Tokutake, T Totsuka, N Toyoshima, F Tusda, T Tsugita, S Tsuji, Y Tsukahara, M Tsuneoka, K Uehara, M Umechara, 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 Englehardt, R J Goldston, E Kallne, J Kallne, H W Jugel, P L Mondiono, F X Solnder, Y Takase, P R Thomas, and K L Wong

Subjects
Electron density, Fusion, Materials science, Nuclear Energy and Engineering, Divertor, Plasma, Atomic physics, JT-60, Condensed Matter Physics, Scaling, Ballooning, Ion
Abstract

From June to October 1987, JT-60 achieved fusion product (ne(0). tau E*.Ti(0)) of 6*1019 m-3.keV.s with hydrogen plasma at plasma current of 2.8 to 3.1 MA with neutral beam power of approximately 20 MW. The central electron density of 1.3*1020 m-3 was obtained at plasma current of 3 MA with 13 approximately 20 MW neutral beam power and the confinement time reached 0.14-0.18 s. An offset linear scaling law like the Shimomura-Odajima scaling on confinement time will be able to reproduce experimental data better than that of the Goldston type scaling. With low beam energy injection approximately 40 keV, confinement degradation was found. Many short periods (0.05 approximately 0.1 s) of H-mode phase were found in outside X-point divertor discharges with NB or NB+RF(LH or IC) heating power above 16 MW. However, improvement in energy confinement time was limited to 10 %. The ballooning/interchange stability analyses were also made for the outside X-point divertor equilibrium in connection with H0-phase capability. Heating powers of 9.5 MW and 1.9 MW were obtained by LHRF, ICRF injection, respectively. In combined LHRF and NB heating, the incremental energy confinement time of 0.064 s was obtained, which is the same level of that of NB heating only. In combined NB and on-axis ICRF heating of low ne discharge, an incremental energy confinement time of 0.21 s was obtained, which is three times as long as those of NB or ICRF heating only. High energy beam ions were accelerated by ICRF in the central region of the plasma.

Published
1988

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