High performance discharges near the operational limit in HT-7

Citation
Jg. Li et al., High performance discharges near the operational limit in HT-7, NUCL FUSION, 41(11), 2001, pp. 1625-1631
Citations number
13
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
NUCLEAR FUSION
ISSN journal
0029-5515 → ACNP
Volume
41
Issue
11
Year of publication
2001
Pages
1625 - 1631
Database
ISI
SICI code
0029-5515(200111)41:11<1625:HPDNTO>2.0.ZU;2-I
Abstract
Efforts have been made on the HT-7 tokamak to extend the stable operation b oundaries. Extensive RF boronization and siliconization have been used and a wider operational Hugill diagram has been obtained. The transit density r eached 1.3 times the Greenwald density limit in ohmic discharges. A station ary high performance discharge with q(alpha) = 2.1 has been obtained after siliconization. Confinement improvement was obtained as a result of the sig nificant reduction of electron thermal diffusivity chi (epsilon) in the out er region of the plasma. An improved confinement phase was also observed wi th 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 de nsity profile. Code simulations and measurements showed good agreement with the off-axis LH wave deposition. Supersonic molecular beam injection has b een successfully used to achieve stable high density operation in the regio n of the Greenwald density limit.