Overview of steady state tokamak plasma experiments in TRIAM-1M

H. Zushi, Sanae Itoh, Kazuaki Hanada, Kazuo Nakamura, M. Sakamoto, Eriko Jotaki, Makoto Hasegawa, Y. D. Pan., S. V. Kulkarni, A. Iyomasa, S. Kawasaki, H. Nakashima, N. Yoshida, Kazutoshi Tokunaga, T. Fujiwara, M. Miyamoto, H. Nakano, M. Yuno, A. Murakami, S. NakamuraN. Sakamoto, K. Shinoda, S. Yamazoe, H. Akanishi, K. Kuramoto, Y. Matsuo, A. Iwamae, T. Fuijimoto, A. Komori, T. Morisaki, H. Suzuki, S. Masuzaki, Y. Hirooka, Y. Nakashima, O. Mitarai

Research output: Contribution to journalArticle

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Abstract

An overview of steady state tokamak studies in TRIAM-1M (R0 = 0.8 m, a × b = 0.12 m × 0.18 m and B = 8T) is presented. The current ramp-up scenario without using centre solenoid coils is reinvestigated with respect to controllability of the current ramp-up rate at the medium density region of (1-2) × 1019 m-3. The plasma is initiated by ECH (fundamental o-mode at 170 GHz with 200 kW) at B = 6.7 T, and the ramp-up rate below the technical limit of 150 kA s-1 for ITER can be achieved by keeping the LH power less than 100 kW during the current ramp-up phase. The physics understanding of the enhanced current drive (ECD) mode around the threshold power level has progressed from a viewpoint of transition probability. A transition frequency, ftrans, for the ECD transition is determined as a function of PCD. At ∼70 kW no transition occurs for an ftrans value of ∼0.017 Hz, meaning almost zero transition probability. With increasing PCD > Pth, ftrans increases up to 10 Hz, and the transition tends to occur with high probability. The record value of the discharge duration is updated to 3 h 10 min in a low n̄e ∼ 1 × 1018 m-3 and low power (<10 kW) discharge. The global particle balance in long duration discharges is investigated, and the temporal change in wall pumping rate is determined. Although the density was low, the gas supply had to be stopped at 30 min after the plasma initiation to maintain the density constant. After that the density was sustained by the recycling flux alone until the end of the discharges. In addition to the recycling problem, in the high power and high density experiments, the localized PWI affects the SSO of the tokamak plasma. The effects of enhanced influx of metal impurities (Fe, Cr, Ni, Mo) on sustainment of the high performance ECD plasma are investigated. In order to evaluate the helium bombarding effects on the plasma facing component and hydrogen recycling in the future burning plasma, microscopic damage of metals exposed to long duration helium discharges was studied. The total exposure time was 128 s. From thermal desorption experiments for the specimens the amount of retained helium was evaluated as 3.9 × 1020 He m-2 and the scale length to be ∼1 mm in the SOL.

Original languageEnglish
Pages (from-to)1600-1609
Number of pages10
JournalNuclear Fusion
Volume43
Issue number12
DOIs
Publication statusPublished - Dec 1 2003

Fingerprint

ramps
recycling
helium
transition probabilities
controllability
solenoids
metals
radiant flux density
pumping
coils
desorption
damage
impurities
physics
thresholds
hydrogen
gases

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Zushi, H., Itoh, S., Hanada, K., Nakamura, K., Sakamoto, M., Jotaki, E., ... Mitarai, O. (2003). Overview of steady state tokamak plasma experiments in TRIAM-1M. Nuclear Fusion, 43(12), 1600-1609. https://doi.org/10.1088/0029-5515/43/12/006

Overview of steady state tokamak plasma experiments in TRIAM-1M. / Zushi, H.; Itoh, Sanae; Hanada, Kazuaki; Nakamura, Kazuo; Sakamoto, M.; Jotaki, Eriko; Hasegawa, Makoto; Pan., Y. D.; Kulkarni, S. V.; Iyomasa, A.; Kawasaki, S.; Nakashima, H.; Yoshida, N.; Tokunaga, Kazutoshi; Fujiwara, T.; Miyamoto, M.; Nakano, H.; Yuno, M.; Murakami, A.; Nakamura, S.; Sakamoto, N.; Shinoda, K.; Yamazoe, S.; Akanishi, H.; Kuramoto, K.; Matsuo, Y.; Iwamae, A.; Fuijimoto, T.; Komori, A.; Morisaki, T.; Suzuki, H.; Masuzaki, S.; Hirooka, Y.; Nakashima, Y.; Mitarai, O.

In: Nuclear Fusion, Vol. 43, No. 12, 01.12.2003, p. 1600-1609.

Research output: Contribution to journalArticle

Zushi, H, Itoh, S, Hanada, K, Nakamura, K, Sakamoto, M, Jotaki, E, Hasegawa, M, Pan., YD, Kulkarni, SV, Iyomasa, A, Kawasaki, S, Nakashima, H, Yoshida, N, Tokunaga, K, Fujiwara, T, Miyamoto, M, Nakano, H, Yuno, M, Murakami, A, Nakamura, S, Sakamoto, N, Shinoda, K, Yamazoe, S, Akanishi, H, Kuramoto, K, Matsuo, Y, Iwamae, A, Fuijimoto, T, Komori, A, Morisaki, T, Suzuki, H, Masuzaki, S, Hirooka, Y, Nakashima, Y & Mitarai, O 2003, 'Overview of steady state tokamak plasma experiments in TRIAM-1M', Nuclear Fusion, vol. 43, no. 12, pp. 1600-1609. https://doi.org/10.1088/0029-5515/43/12/006
Zushi, H. ; Itoh, Sanae ; Hanada, Kazuaki ; Nakamura, Kazuo ; Sakamoto, M. ; Jotaki, Eriko ; Hasegawa, Makoto ; Pan., Y. D. ; Kulkarni, S. V. ; Iyomasa, A. ; Kawasaki, S. ; Nakashima, H. ; Yoshida, N. ; Tokunaga, Kazutoshi ; Fujiwara, T. ; Miyamoto, M. ; Nakano, H. ; Yuno, M. ; Murakami, A. ; Nakamura, S. ; Sakamoto, N. ; Shinoda, K. ; Yamazoe, S. ; Akanishi, H. ; Kuramoto, K. ; Matsuo, Y. ; Iwamae, A. ; Fuijimoto, T. ; Komori, A. ; Morisaki, T. ; Suzuki, H. ; Masuzaki, S. ; Hirooka, Y. ; Nakashima, Y. ; Mitarai, O. / Overview of steady state tokamak plasma experiments in TRIAM-1M. In: Nuclear Fusion. 2003 ; Vol. 43, No. 12. pp. 1600-1609.
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AU - Zushi, H.

AU - Itoh, Sanae

AU - Hanada, Kazuaki

AU - Nakamura, Kazuo

AU - Sakamoto, M.

AU - Jotaki, Eriko

AU - Hasegawa, Makoto

AU - Pan., Y. D.

AU - Kulkarni, S. V.

AU - Iyomasa, A.

AU - Kawasaki, S.

AU - Nakashima, H.

AU - Yoshida, N.

AU - Tokunaga, Kazutoshi

AU - Fujiwara, T.

AU - Miyamoto, M.

AU - Nakano, H.

AU - Yuno, M.

AU - Murakami, A.

AU - Nakamura, S.

AU - Sakamoto, N.

AU - Shinoda, K.

AU - Yamazoe, S.

AU - Akanishi, H.

AU - Kuramoto, K.

AU - Matsuo, Y.

AU - Iwamae, A.

AU - Fuijimoto, T.

AU - Komori, A.

AU - Morisaki, T.

AU - Suzuki, H.

AU - Masuzaki, S.

AU - Hirooka, Y.

AU - Nakashima, Y.

AU - Mitarai, O.

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N2 - An overview of steady state tokamak studies in TRIAM-1M (R0 = 0.8 m, a × b = 0.12 m × 0.18 m and B = 8T) is presented. The current ramp-up scenario without using centre solenoid coils is reinvestigated with respect to controllability of the current ramp-up rate at the medium density region of (1-2) × 1019 m-3. The plasma is initiated by ECH (fundamental o-mode at 170 GHz with 200 kW) at B = 6.7 T, and the ramp-up rate below the technical limit of 150 kA s-1 for ITER can be achieved by keeping the LH power less than 100 kW during the current ramp-up phase. The physics understanding of the enhanced current drive (ECD) mode around the threshold power level has progressed from a viewpoint of transition probability. A transition frequency, ftrans, for the ECD transition is determined as a function of PCD. At ∼70 kW no transition occurs for an ftrans value of ∼0.017 Hz, meaning almost zero transition probability. With increasing PCD > Pth, ftrans increases up to 10 Hz, and the transition tends to occur with high probability. The record value of the discharge duration is updated to 3 h 10 min in a low n̄e ∼ 1 × 1018 m-3 and low power (<10 kW) discharge. The global particle balance in long duration discharges is investigated, and the temporal change in wall pumping rate is determined. Although the density was low, the gas supply had to be stopped at 30 min after the plasma initiation to maintain the density constant. After that the density was sustained by the recycling flux alone until the end of the discharges. In addition to the recycling problem, in the high power and high density experiments, the localized PWI affects the SSO of the tokamak plasma. The effects of enhanced influx of metal impurities (Fe, Cr, Ni, Mo) on sustainment of the high performance ECD plasma are investigated. In order to evaluate the helium bombarding effects on the plasma facing component and hydrogen recycling in the future burning plasma, microscopic damage of metals exposed to long duration helium discharges was studied. The total exposure time was 128 s. From thermal desorption experiments for the specimens the amount of retained helium was evaluated as 3.9 × 1020 He m-2 and the scale length to be ∼1 mm in the SOL.

AB - An overview of steady state tokamak studies in TRIAM-1M (R0 = 0.8 m, a × b = 0.12 m × 0.18 m and B = 8T) is presented. The current ramp-up scenario without using centre solenoid coils is reinvestigated with respect to controllability of the current ramp-up rate at the medium density region of (1-2) × 1019 m-3. The plasma is initiated by ECH (fundamental o-mode at 170 GHz with 200 kW) at B = 6.7 T, and the ramp-up rate below the technical limit of 150 kA s-1 for ITER can be achieved by keeping the LH power less than 100 kW during the current ramp-up phase. The physics understanding of the enhanced current drive (ECD) mode around the threshold power level has progressed from a viewpoint of transition probability. A transition frequency, ftrans, for the ECD transition is determined as a function of PCD. At ∼70 kW no transition occurs for an ftrans value of ∼0.017 Hz, meaning almost zero transition probability. With increasing PCD > Pth, ftrans increases up to 10 Hz, and the transition tends to occur with high probability. The record value of the discharge duration is updated to 3 h 10 min in a low n̄e ∼ 1 × 1018 m-3 and low power (<10 kW) discharge. The global particle balance in long duration discharges is investigated, and the temporal change in wall pumping rate is determined. Although the density was low, the gas supply had to be stopped at 30 min after the plasma initiation to maintain the density constant. After that the density was sustained by the recycling flux alone until the end of the discharges. In addition to the recycling problem, in the high power and high density experiments, the localized PWI affects the SSO of the tokamak plasma. The effects of enhanced influx of metal impurities (Fe, Cr, Ni, Mo) on sustainment of the high performance ECD plasma are investigated. In order to evaluate the helium bombarding effects on the plasma facing component and hydrogen recycling in the future burning plasma, microscopic damage of metals exposed to long duration helium discharges was studied. The total exposure time was 128 s. From thermal desorption experiments for the specimens the amount of retained helium was evaluated as 3.9 × 1020 He m-2 and the scale length to be ∼1 mm in the SOL.

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