The background magnets of the Samsung Superconductor Test Facility (SSTF)

The background magnet system of SSTF (Samsung Superconductor Test Facility) for KSTAR (Korea Superconducting Tokamak Advanced Research) is now under design. The main coil (MC) is split solenoids and the gap can be changed from 0 to 750 mm. The ID of MC is 750 mm. It will be wound using a CICC (cable-in-conduit conductor) designed for the central solenoid of KSTAR. The central field is 8 T at 22.5 kA when the gap is 250 mm. The ramp rate of MC is 3 T/s. A pair of blip coils will simulate (during the discharge) 1 T amplitude and 20 T/s rate electromagnetic disturbances expected from the KSTAR operation. To compensate the inductive interaction between MC and blip coils during the discharge of the blip coils, a pair of cancellation coils is foreseen. Both blip and cancellation coils (BCC) are fed in series and generate 1 T central field at 7 kA and 250 mm gap. The BCC are wound with CICC and cooled internally and externally.