Open AccessParticle control in long-pulse discharge using divertor pumping in LHD
Author(s) -
G. Motojima,
S. Masuzaki,
T. Morisaki,
K. Y. Watanabe,
M. Kobayashi,
K. Ida,
R. Sakamoto,
M. Yoshinuma,
R. Seki,
Hideo Nuga,
Toru Ii Tsujimura,
C. Suzuki,
M. Emoto,
Y. Tsuchibushi,
T. Murase,
Y. Takeiri
Publication year - 2022
Publication title -
physica scripta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.415
H-Index - 83
eISSN - 1402-4896
pISSN - 0031-8949
DOI - 10.1088/1402-4896/ac5269
Subject(s) - divertor , materials science , atomic physics , plasma , electron temperature , neutral particle , electron , electron density , particle (ecology) , physics , tokamak , nuclear physics , oceanography , geology
Density control is crucial for maintaining stable confined plasma. Divertor pumping, where neutral particles are compressed and exhausted in the divertor region, was developed for this task for the Large Helical Device. In this study, neutral particle pressure, which is related to recycling, was systematically scanned in the magnetic configuration by changing the magnetic axis position. High neutral particle pressure and compression were obtained in the divertor for a high plasma electron density and the inner magnetic axis configuration. Density control using divertor pumping with gas puffing was applied to electron cyclotron heated plasma in the inner magnetic axis configuration, which provides high neutral particle compression and exhaust in the divertor. Stable plasma density and electron temperature were maintained with divertor pumping. A heat analysis shows that divertor pumping did not affect edge electron heat conductivity, but it led to low electron heat conductivity in the core caused by electron-internal-transport-barrier-like formation.