Design, development and operation of superconducting system for
LHD ABSTRACT The Large Helical Device (LHID) of National
Institute for Fusion Science (NIFS) is a heliotron-type
experimental fusion device which has the capability of confining
current-less and steady-state plasma. The primary feature on the
engineering aspect of LHD is using superconducting coils for
magnetic confinement: two pool boiling helical coils (H1, H2)
and three pairs of forced-flow poloidal coils (IV, IS, OV) wound
with cable-in-conduit conductors (CICC). The maximum magnetic
field at plasma center is 3 T in the Phase I experiment and 4 T
in Phase II, while its stored energy becomes 0.9 GJ and 1.6 GJ,
respectively. These coils are connected to the power supplies by
superconducting bus-lines with their nominal current of 31.3 kA.
The construction of LHD started in 1991 and was completed by the
end of 1997. During this period, extensive research and
development were conducted to complete a large-scale
superconducting system. The plasma