Hydraulic Characteristics of ITER TF Insert Coil

The Central Solenoid (CS) model coil program was established in 1992 as one of projects for the Engineering Design Activities of the International Thermonuclear Experimental Reactor (ITER) and has been an ongoing activity ever since. A CS model coil and a Toroidal Field (TF) Insert have been developed and tested successfully. The TF insert is comprised of a cable-in-conduit conductor that consists of 1, 152 superconducting strands bundled on a central cooling channel. An experiment was conducted to investigate the pressure drop performance of the TF insert. There were two purposes for the investigation: one to verify pressure drop prediction using correlations proposed by various researchers, and other to investigate the behavior of the pressure drop under electromagnetic forces. The pressure drop of the TF insert decreased by approximately 12% during current-carrying operation of 46kA at 13T. After several current-carrying operations, the friction factor of the TF insert finally reached a value that was approximately 10% lower than that of original state and was not recovered even without current. It is believed that the cable cross-section inside the conductor jacket became deformed due to electromagnetic force and a new flow path in the jacket was generated.