Improved confinement mode induced by the MARFE on the HT-7 superconductingtokamak

Citation
X. Gao et al., Improved confinement mode induced by the MARFE on the HT-7 superconductingtokamak, PLASMA PHYS, 41(11), 1999, pp. 1349-1355
Citations number
15
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
PLASMA PHYSICS AND CONTROLLED FUSION
ISSN journal
0741-3335 → ACNP
Volume
41
Issue
11
Year of publication
1999
Pages
1349 - 1355
Database
ISI
SICI code
0741-3335(199911)41:11<1349:ICMIBT>2.0.ZU;2-2
Abstract
Ln the HT-7 superconducting tokamak, the onset of a multifaceted asymmetric radiation from the edge (MARFE) usually occurs in the early ohmic discharg es of each experimental campaign before wall conditioning. The occurrence a nd location of a MARFE is identified by different diagnostic systems. An im proved confinement mode plasma which was induced by the MARFE is observed, and the global particle confinement time increases 1.9 times. The relaxatio n time between the MARFE event trigger and the L-H transition is about 1.4 ms, the following L-H transition time is 1.9 ms, and the improved confineme nt mode phase is maintained for about 40 ms. The MARFE cools the plasma edg e, and the electron density profile is observed to become more narrow and p eaked. The occurrence of a MARFE is strongly correlated with Z(eff) but not with the density, and it always occurs at Z(eff) = 3-8 ohmic discharges. I n the case of a good wall condition (Z(eff) = 1-2), the onset of MARFEs has not been observed before reaching the Greenwald density limit.