Quench Analysis of the KSTAR TF Magnets and Bus Lines for the First Campaign

In the Korea Superconducting Tokamak Advanced Research(KSTAR) device, the Toroidal Field (TF) coils were manufactured with ${\rm Nb}_{3}{\rm Sn}$, and the bus lines with NbTi, and all the coils are cooled by supercritical helium. During the first campaign, the TF coils were operated with a steady state current of 15 kA. In case of a quench the conductor is being developed due to an unexpected effect on the superconducting strands, the current should be discharged into an external dump resistor for protection of the magnet. The development or recovery of the quench is related to the protection triggering delay time and the quench voltage. The thermo-hydraulic phenomena were simulated by the GANDALF code and the initial quench propagation condition was found from the minimum quench energy and the initial quench zone. In this paper, we determined the quench voltage level and trigger time by analysis of temperature, voltage, and pressure growth, in the magnet and bus lines, with triggering delays of ${\rm t}=2\ {\rm s}$, 3 s, 4 s, and 5 s, by analysing the effects of a temperature and voltage growth of the magnet and bus lines.