Study of Edge Transport Barrier Formation on CHS Plasma

An edge transport barrier (ETB) similar to the tokamak H-mode has been observed for beam-heated plasma with two co-injected Neutral Beam Injectors (NBIs) in CHS. The Hα emission showed a clear spontaneous drop followed by an increase of line-averaged electron density at the L-H transition. Stored en...

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Bibliographic Details
Published in:Plasma and Fusion Research 2006, Vol.1, pp.032-032
Main Authors: MINAMI, Takashi, OKAMURA, Shoichi, AKIYAMA, Tsuyoshi, ISOBE, Mitsutaka, OHISHI, Tetsutaro, NAKANO, Haruhisa, IDA, Katsumi, FUJISAWA, Akihide, NAKAMURA, Kiichiro, NAGAOKA, Kenichi, YOSHINUMA, Mikiro, SUZUKI, Chihiro, YOSHIMURA, Yasuo, TOI, Kazuo, NISHIURA, Masaki, OHSHIMA, Shinsuke, NARUHIRO, Zenzo, IGUCHI, Harukazu, NISHIMURA, Shin, SHIMIZU, Akihiro, MATSUOKA, Keisuke, TAKAHASHI, Chihiro
Format: Article
Language:English
Subjects:
Barriers
CHS
Density
edge transport barrier
Electron density
H-mode
H-mode scaling
helical plasma
improved confinement
Magnetic fields
plasma confinement
Strength
threshold power
Thresholds
Tokamak devices
Transport
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Summary:An edge transport barrier (ETB) similar to the tokamak H-mode has been observed for beam-heated plasma with two co-injected Neutral Beam Injectors (NBIs) in CHS. The Hα emission showed a clear spontaneous drop followed by an increase of line-averaged electron density at the L-H transition. Stored energy increased by ˜ 40% with H-factor improvement up to ˜ 30% compared to the international stellarator scaling (ISS04v03). A rapid density increase in the edge region to two-times level of the L-mode was observed to accompany a ˜ 15% increase in the density gradient. An ETB was formed when the plasma density exceeded the lower density limit by ˜ 1.5 × 1013 cm-3 and the total NBI power exceeds the threshold level (Pdeposit / ne ˜ 200 × 10-13 kW/cm-3 at BT = 0.95 T, Rax = 92.1 cm, where Pdeposit is the deposited NBI power, ne is electron density, BT is troidal magnetic field strength and Rax is location of magnetic axis). The power threshold increased with the magnetic field strength, as in tokamak scaling, and depends on the magnetic field configuration of the helical plasma.
ISSN:1880-6821
1880-6821
DOI:10.1585/pfr.1.032