High performance discharges near the operational limit in HT-7

Efforts have been made on the HT-7 tokamak to extend the stable operation boundaries. Extensive RF boronization and siliconization have been used and a wider operational Hugill diagram has been obtained. The transit density reached 1.3 times the Greenwald density limit in ohmic discharges. A station...

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Bibliographic Details
Published in:Nuclear fusion 2001-11, Vol.41 (11), p.1625-1631
Main Authors: Li, Jiangang, Wan, Baonian, Luo, Jiarong, Gao, Xiang, Zhao, Yanping, Kuang, Guangli, Zhang, Xiaodong, Yang, Yu, Bao, Yi, Ding, Bojiang, Xie, Jikang, Wan, Yuanxi, Group, HT-7
Format: Article
Language:English
Subjects:
Computer simulation
Current density
Deposition
Electric discharges
Exact sciences and technology
High-frequency discharges
Magnetic confinement and equilibrium
Molecular beams
Ohmic contacts
Physics
Physics of gases, plasmas and electric discharges
Physics of plasmas and electric discharges
Plasma theory
Radiation
Thermal diffusion
Tokamaks
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Summary:Efforts have been made on the HT-7 tokamak to extend the stable operation boundaries. Extensive RF boronization and siliconization have been used and a wider operational Hugill diagram has been obtained. The transit density reached 1.3 times the Greenwald density limit in ohmic discharges. A stationary high performance discharge with q sub(a) = 2.1 has been obtained after siliconization. Confinement improvement was obtained as a result of the significant reduction of electron thermal diffusivity Chi sub(e) in the outer region of the plasma. An improved confinement phase was also observed with LHCD in the density range of 70-120% of the Greenwald density limit. Off-axis LH wave power deposition was attributed to the weak hollow current density profile. Code simulations and measurements showed good agreement with the off-axis LH wave deposition. Supersonic molecular beam injection has been successfully used to achieve stable high density operation in the region of the Greenwald density limit.
ISSN:0029-5515
1741-4326
DOI:10.1088/0029-5515/41/11/312