The cold test facility will be located in the partially vacated poloidal field coil winding facility. Supercritical helium at 4 K will be delivered by way of a cryogenic auxiliary cold box (blue) interfacing with the cryoplant; electrical power will be fed by a busbar (orange) originating in a dedicated power supply system. Both cryogens and electrical power will be delivered to the magnet by way of a feeder (yellow). As the coil will be in the horizontal position, a new design is required for connecting it to the feeder.
"Testing at 4 K and at 80 K are completely different operations," explains David Grillot, °ÄÃÅÁùºÏ²Ê¸ßÊÖ deputy program manager for plant systems and former leader of the Cryogenics Section. "Considering that a toroidal field coil's mass is in excess of 300 tonnes, the colder test requires considerable infrastructure—a large cryostat, a dedicated power supply, an electrical feeder and associated instrumentation, and an interface with a large refrigerator located inside the cryoplant. It's not comparable at all to testing at 80 K, which is relatively simple and has been done routinely."
Designed to accommodate the tokamak's D-shaped toroidal field coils, the dimensions of the cold test facility's cryostat (11 m x 22 m) will also allow for the testing of poloidal field coil #1 (10 m in diameter).
But the mood has changed and "a window of opportunity" has opened. The