Testing of the Euratom LCT-coil, a forced-flow cooled NbTi coil, in the international fusion superconducting magnet test facility (IFSMTF)

The Euratom-LCT-coil was tested as a single coil in the TOSKA facility at KfK Karlsruhe and in IFSMTF at ORNL Oak Ridge. Different mechanical boundary conditions and other operation parameters (mass flow, current) in the IFSMTF led to new set of results which broaden the knowledge about the coil. During cooldown the coil showed excellent heat transfer properties. The design current 11.4 kA with a max. field of 6.63 T could be reached with a ramp rate of 4 A/S without visible instabilities and thermal losses. The coil had at rated current a Stekly parameter α = 2.3 and could safely operated outside the cryogenic stability regime. The coil was 7 times dumped from currents higher than 4 kA with a peak voltage of 2.5 kV. Pressure increase was investigated under different boundary conditions and remained moderate. Dump losses measured were about 2 % of the stored energy. The coil was two times quenched during investigation of the operation limits. The quench detection system specially developed for this coil could be successfully tested with a level setting of 50 mV. For the first time the operation limits of such a coil were determined by current sharing measurement with heated helium slugs. The results are in fair agreement with those extrapolated from single strand measurements.