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O. Motojima, K. Akaishi, H. Chikaraishi,
H. Funaba, S. Hamaguchi, S. Imagawa, S. Inagaki,
N. Inoue, A. Iwamoto, S. Kitagawa, A. Komori,
Y. Kubota, R. Maekawa, S. Masuzaki, T. Mito,
J. Miyazawa, T. Morisaki, K. Murai, T. Muroga,
T. Nagasaka, Y. Nakamura, A. Nishimura,
K. Nishimura, N. Noda, N. Ohyabu, A. Sagara,
S. Sakakibara, R. Sakamoto, S. Satoh, T. Satow,
M. Shoji, H. Suzuki, K. Takahata, H. Tamura,
K. Watanabe, H. Yamada, S. Yamada, S. Yamaguchi,
K. Yamazaki, N. Yanagi, T. Baba, H. Hayashi,
M. Iima, T. Inoue, S. Kato, T. Kato, T. Kondo,
S. Moriuchi, H. Ogawa, I. Ohtake, K. Ooba,
H. Sekiguchi, N. Suzuki, S. Takami, Y. Taniguchi,
T. Tsuzuki, N. Yamamoto, K. Yasui, H. Yonezu,
M. Fujiwara, A. Iiyoshi
National Institute for Fusion Science, 322-6 Oroshicho, Toki 509-5292, Japan
Abstract. In March 1998, the large helical device (LHD) project finally
completed its 8 years construction schedule. LHD is a superconducting (SC)
heliotron type device with R=3.9 m,
ap =0.6 m, and B=3 T, which has
simplex
and continuous large helical coils. The major mission of LHD is to demonstrate
the high potential of currentless helical-toroidal plasmas, which are free
from current disruption and have an intrinsic potential for steady state
operation. After the intensive physics design studies in the 1980's, the
necessary programs of SC engineering R&D were made and carried out, and as a
result, LHD fabrication technologies were successfully developed. In this
process, a significant database on fusion engineering has been
established. These achievements have been made in various areas, such as the
technologies of SC conductor development, SC coil fabrication, liquid helium
(LHe) and supercritical helium (SHe) cryogenics, development of low
temperature structural materials and welding, operation and control, and power
supply systems and related SC coil protection schemes. They are integrated,
and nowadays comprise a major part of the LHD relevant fusion technology
area. These issues correspond to a necessary technological data base for the
next step of future reactor designs. In addition, we could increase this with
successful commissioning tests just after the completion of LHD machine
assembly phase, which consisted of vacuum leak test, LHe cooldown test, and
coil current excitation test. We recapitulate and highlight these LHD relevant
engineering developments in this paper. To summarize our construction of LHD
as an SC device, the critical design with NbTi SC material has been
successfully accomplished by our R&D activities, which enables us to move into
a new regime of fusion experiments.
IAEA 2001
