Abstract
The large helical device (LHD) is the world largest helical system having all superconducting coils. After completion of LHD in 1998, six experimental campaigns have been carried out successfully. The maximum stored energy, central electron temperature, and volume average beta value are 1.16 MJ, 10 keV, and 3.2%, respectively. The confinement time of the LHD plasma appears to be equivalent to that of tokamaks. One of the most important missions for LHD is to prove stead-state operation, which is also significant to international thermonuclear experimental reactor (ITER) and to future fusion reactors. LHD is quite appropriate for this purpose based upon the beneficial feature of a helical system, that is, no necessity of the plasma current. So far, the plasma discharge duration was achieved up to 150 s. The plasma density was kept constant by feedback control of gas puffing with real time information of the line density. The issue for demonstrating steady-state operation is whether divertor function to control particle and heat flux is effective enough. Relevant to this, LHD diagnostics should be consistent with the following: 1) continuous operation of main diagnostics during long-pulse operation for feedback control and physics understanding; 2) measurement of fraction of H, He, and impurities in the plasma; 3) heat removal and measure against possible damage or surface erosion of diagnostic components inside of the vacuum chamber; 4) data acquisition system for handling real time data display and a huge amount of data. Although there are already some achievements on the above subjects, there remain still several issues to be resolved. On the other hand, the long-pulse operation of the plasma gives benefits to the diagnostics. For example, the polarizing angle of ECE emission can be changed during the discharge, and the intensity dependence on the polarizing angle has been obtained. The spatial scanning of the neutral particle analyzer and the spectrometer can supply the spatial profiles of the fast neutral particle flux and the specific impurity lines. In this paper, the present status of these issues and future plans are described.
| Original language | English |
|---|---|
| Pages (from-to) | 167-176 |
| Number of pages | 10 |
| Journal | IEEE Transactions on Plasma Science |
| Volume | 32 |
| Issue number | 1 I |
| DOIs | |
| Publication status | Published - Feb 1 2004 |
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All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Condensed Matter Physics
Cite this
LHD diagnostics toward steady-state operation. / Sudo, Shigeru; Peterson, Byron J.; Kawahata, Kazuo; Nagayama, Yoshio; Narihara, K.; Hamada, Yasuji; Toi, K.; Ida, Katsumi; Iguchi, Harukazu; Sato, Kuninori; Morita, S.; Ozaki, Tetsuo; Nishizawa, Akimitsu; Tanaka, Kenji; Minami, T.; Yamada, Ichihiro; Mutoh, S.; Emoto, Masahiko; Nakanishi, Hideya; Goto, M.; Ohdachi, Satoshi; Tokuzawa, Tokihiko; Inagaki, Shigeru; Ido, Takeshi; Yoshinuma, M.; Sakakibara, Satoru; Masuzaki, S.; Morisaki, Tomohiro; Shoji, Mamoru; Osakabe, M.; Ashikawa, Naoko.
In: IEEE Transactions on Plasma Science, Vol. 32, No. 1 I, 01.02.2004, p. 167-176.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - LHD diagnostics toward steady-state operation
AU - Sudo, Shigeru
AU - Peterson, Byron J.
AU - Kawahata, Kazuo
AU - Nagayama, Yoshio
AU - Narihara, K.
AU - Hamada, Yasuji
AU - Toi, K.
AU - Ida, Katsumi
AU - Iguchi, Harukazu
AU - Sato, Kuninori
AU - Morita, S.
AU - Ozaki, Tetsuo
AU - Nishizawa, Akimitsu
AU - Tanaka, Kenji
AU - Minami, T.
AU - Yamada, Ichihiro
AU - Mutoh, S.
AU - Emoto, Masahiko
AU - Nakanishi, Hideya
AU - Goto, M.
AU - Ohdachi, Satoshi
AU - Tokuzawa, Tokihiko
AU - Inagaki, Shigeru
AU - Ido, Takeshi
AU - Yoshinuma, M.
AU - Sakakibara, Satoru
AU - Masuzaki, S.
AU - Morisaki, Tomohiro
AU - Shoji, Mamoru
AU - Osakabe, M.
AU - Ashikawa, Naoko
PY - 2004/2/1
Y1 - 2004/2/1
N2 - The large helical device (LHD) is the world largest helical system having all superconducting coils. After completion of LHD in 1998, six experimental campaigns have been carried out successfully. The maximum stored energy, central electron temperature, and volume average beta value are 1.16 MJ, 10 keV, and 3.2%, respectively. The confinement time of the LHD plasma appears to be equivalent to that of tokamaks. One of the most important missions for LHD is to prove stead-state operation, which is also significant to international thermonuclear experimental reactor (ITER) and to future fusion reactors. LHD is quite appropriate for this purpose based upon the beneficial feature of a helical system, that is, no necessity of the plasma current. So far, the plasma discharge duration was achieved up to 150 s. The plasma density was kept constant by feedback control of gas puffing with real time information of the line density. The issue for demonstrating steady-state operation is whether divertor function to control particle and heat flux is effective enough. Relevant to this, LHD diagnostics should be consistent with the following: 1) continuous operation of main diagnostics during long-pulse operation for feedback control and physics understanding; 2) measurement of fraction of H, He, and impurities in the plasma; 3) heat removal and measure against possible damage or surface erosion of diagnostic components inside of the vacuum chamber; 4) data acquisition system for handling real time data display and a huge amount of data. Although there are already some achievements on the above subjects, there remain still several issues to be resolved. On the other hand, the long-pulse operation of the plasma gives benefits to the diagnostics. For example, the polarizing angle of ECE emission can be changed during the discharge, and the intensity dependence on the polarizing angle has been obtained. The spatial scanning of the neutral particle analyzer and the spectrometer can supply the spatial profiles of the fast neutral particle flux and the specific impurity lines. In this paper, the present status of these issues and future plans are described.
AB - The large helical device (LHD) is the world largest helical system having all superconducting coils. After completion of LHD in 1998, six experimental campaigns have been carried out successfully. The maximum stored energy, central electron temperature, and volume average beta value are 1.16 MJ, 10 keV, and 3.2%, respectively. The confinement time of the LHD plasma appears to be equivalent to that of tokamaks. One of the most important missions for LHD is to prove stead-state operation, which is also significant to international thermonuclear experimental reactor (ITER) and to future fusion reactors. LHD is quite appropriate for this purpose based upon the beneficial feature of a helical system, that is, no necessity of the plasma current. So far, the plasma discharge duration was achieved up to 150 s. The plasma density was kept constant by feedback control of gas puffing with real time information of the line density. The issue for demonstrating steady-state operation is whether divertor function to control particle and heat flux is effective enough. Relevant to this, LHD diagnostics should be consistent with the following: 1) continuous operation of main diagnostics during long-pulse operation for feedback control and physics understanding; 2) measurement of fraction of H, He, and impurities in the plasma; 3) heat removal and measure against possible damage or surface erosion of diagnostic components inside of the vacuum chamber; 4) data acquisition system for handling real time data display and a huge amount of data. Although there are already some achievements on the above subjects, there remain still several issues to be resolved. On the other hand, the long-pulse operation of the plasma gives benefits to the diagnostics. For example, the polarizing angle of ECE emission can be changed during the discharge, and the intensity dependence on the polarizing angle has been obtained. The spatial scanning of the neutral particle analyzer and the spectrometer can supply the spatial profiles of the fast neutral particle flux and the specific impurity lines. In this paper, the present status of these issues and future plans are described.
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UR - http://www.scopus.com/inward/citedby.url?scp=2442671672&partnerID=8YFLogxK
U2 - 10.1109/TPS.2004.823896
DO - 10.1109/TPS.2004.823896
M3 - Article
AN - SCOPUS:2442671672
VL - 32
SP - 167
EP - 176
JO - IEEE Transactions on Plasma Science
JF - IEEE Transactions on Plasma Science
SN - 0093-3813
IS - 1 I
ER -