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(EX/P2-16) Radial Electric Field and Transport near the Rational Surface and the Magnetic Island in LHD
K. Ida1),
S. Inagaki1),
N. Tamura1),
T. Morisaki1),
N. Ohyabu1),
K. Khlopenkov1),
S. Sudo1),
K. Watanabe1),
M. Yokoyama1),
T. Shimozuma1),
Y. Takeiri1),
K. Itoh1),
M. Yoshinuma1),
Y. Liang1),
K. Narihara1),
K. Tanaka1),
Y. Nagayama1),
T. Tokuzawa1),
K. Kawahata1),
H. Suzuki1),
A. Komori1),
T. Akiyama2),
N. Ashikawa1),
M. Emoto1),
H. Funaba1),
P. Goncharov3),
M. Goto1),
H. Idei1),
K. Ikeda1),
M. Isobe1),
O. Kaneko1),
H. Kawazome4),
T. Kobuchi1),
A. Kostrioukov1),
S. Kubo1),
R. Kumazawa1),
S. Masuzaki1),
T. Minami1),
J. Miyazawa1),
S. Morita1),
S. Murakami1),
S. Muto1),
T. Mutoh1),
Y. Nakamura1),
H. Nakanishi1),
Y. Narushima1),
K. Nishimura1),
N. Noda1),
T. Notake5),
H. Nozato6),
S. Ohdachi1),
Y. Oka1),
M. Osakabe1),
T. Ozaki1),
B.J. Peterson1),
A. Sagara1),
T. Saida3),
K. Saito1),
S. Sakakibara1),
R. Sakamoto1),
M. Sasao1),
K. Sato1),
M. Sato1),
T. Seki1),
M. Shoji1),
N. Takeuchi5),
K. Toi1),
Y. Torii5),
K. Tsumori1),
T. Watari1),
Y. Xu1),
H. Yamada1),
I. Yamada1),
S. Yamamoto5),
T. Yamamoto5),
Y. Yoshimura1),
I. Ohtake1),
K. Ohkubo1),
T. Mito1),
T. Satow1),
T. Uda1),
K. Yamazaki1),
K. Matsuoka1),
O. Motojima1),
M. Fujiwara1)
1) National Institute for Fusion Science, Toki, Japan
2) Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo, Japan
3) Department of Fusion Science, School of Mathematical and Physical Science, Graduate University for Advanced Studies, Hayama, Japan
4) Graduate School of Energy Science, Kyoto University, Uji, Japan
5) Department of Energy Engineering and Science, Nagoya University, Japan
6) Graduate School of Frontier Sciences, The University of Tokyo, Japan
Abstract. The structures of radial electric field and transport at the
magnetic island are investigated using n/m=1/1 external perturbation coils
in the Large Helical Device (LHD). The radial profiles of plasma potential,
as well as the electron temperature and density, shows flattening inside the
magnetic island and the large shear of the radial electric field is observed
at the boundary of the magnetic island. When the current of n/m=1/1 external
perturbation coils becomes large enough, the finite radial electric field
appears inside the magnetic island. The abrupt appearance of plasma flow
inside the magnetic island suggests the non-linearity of the viscous force
at the boundary of the magnetic island. The thermal diffusivity
perpendicular to the magnetic filed inside the magnetic island is estimated
with the cold pulse propagation, which is produced by a tracer-encapsulated
solid pellet (TESPEL). The time delay and amplitude of the electron
temperature of the cold pulse show much lower thermal diffusivity inside the
magnetic island (
0.3m2/s) than that outside the magnetic island (
6m2/s), which is a clear evidence for the significant reduction of heat
transport inside the magnetic island.
IAEA 2003