(EXP4/18) Impact of Pellet Injection on Extension of Operational Region in
LHD
R. Sakamoto1), H. Yamada1),
K. Tanaka1), K. Narihara1), S. Morita1),
S. Sakakibara1), S. Masuzaki1),
L. R. Baylor2), P. W. Fisher2),
S. K. Combs2), M. J. Gouge2), S. Kato1),
A. Komori1), O. Kaneko1), N. Ashikawa3),
P. de Vries1), M. Emoto1), H. Funaba1),
M. Goto1), K. Ida1), H. Idei1),
K. Ikeda1), S. Inagaki1), M. Isobe1),
S. Kado1), K. Kawahata1),
K. Khlopenkov1), S. Kubo1),
R. Kumazawa1), T. Minami1),
J. Miyazawa1), T. Morisaki1),
S. Murakami1), S. Muto1), T. Mutoh1),
Y. Nagayama1), Y. Nakamura1),
H. Nakanishi1), K. Nishimura1),
N. Noda1), T. Notake4), T. Kobuchi3),
Y. Liang3), S. Ohdachi1), N. Ohyabu1),
Y. Oka1), M. Osakabe1), T. Ozaki1),
R. O. Pavlichenko1), B. J. Peterson1),
A. Sagara1), K. Saito4), H. Sasao3),
M. Sasao1), K. Sato1), M. Sato1),
T. Seki1), T. Shimozuma1), M. Shoji1),
S. Sudo1), H. Suzuki1), M. Takechi1),
Y. Takeiri1), N. Tamura3), K. Toi1),
T. Tokuzawa1), Y. Torii4), K. Tsumori1),
I. Yamada1), S. Yamaguchi1),
S. Yamamoto4), Y. Yoshimura1),
K. Y. Watanabe1), T. Watari1),
K. Yamazaki1), Y. Hamada1),
O. Motojima1), M. Fujiwara1)
1) National Institute for Fusion Science, Toki,
Gifu 509-5292, Japan
2) Oak Ridge National Laboratory, PO Box 2009, Oak Ridge,
TN 37831-8071, USA
3) Department of Fusion Science, School of Mathematical and Physical
Science, Graduate University for Advanced Studies, Hayama, 240-0193, Japan
4) Department of Energy Engineering and Science, Nagoya University,
464-8603, Japan
Abstract. Pellet injection has been used as a primary fueling scheme in
Large Helical Device (LHD). Pellet injection has extended an operational
region of NBI plasmas to higher densities with maintaining preferable
dependence of energy confinement on density, and achieved several important
data, such as plasma stored energy (0.88 MJ), energy confinement time (0.3
s), (2.4 % at 1.3 T) and density (
1.1×1020m- 3).
These parameters cannot be attained by gas puffing. Ablation and subsequent
behavior of plasma has been investigated. Measured pellet penetration depth
that is estimated by duration of the
H emission is shallower
than predicted penetration depth from the simple neutral gas shielding (NGS)
model. The penetration depth can be explained by NGS model with fast ion
effect on the ablation. Just after ablation, redistribution of ablated
pellet mass was observed in short time (
400ms). The
redistribution causes shallow deposition and low fueling efficiency.
IAEA 2001