1997 Volume 32 Issue 11 Pages 580-585
We conducted cool-down and excitation tests of an IV coil using the test facilities at the cryogenics and superconductivity laboratories of the NIFS. The main purpose of this experiment was to confirm the designed coils parameters before installing them in the Large Herical Device (LHD) cryostat. The other purpose was to demonstrate operations of a large SHe forced-flow coil, as an example of a total superconducting system including a cryogenic system, a superconducting bus line, a power supply and a protection system. The first experiment was carried out from the end of January to the beginning of March 1995. The coil could be cooled down to the superconducting state for 23 days including cooling suspension times. An inlet filter of the coil was, however, repeatedly blocked with impurities in helium gas during cool-down and steady operation. Due to the unstable operation of the cooling system, the excitation test was limited to 2.2kA. The second experiment was conducted from November to early December 1995. We readjusted the test facilities by increasing the cooling ability of LHe storage and adapting a new inlet-filter unit. The test facilities could be operated steadily, and the coil was successfully energized up to the LHD nominal current, 20.8kA.
