Performance of the Quench Detection System for the KSTAR CS Magnet System

The Korea Superconducting Tokamak Advanced Research (KSTAR) Central Solenoid (CS) magnet system coils are made of Cable-In-Conduit Conductors (CICC) that contains 240 strands and 120 copper strands inside an Incoloy 908 jacket. It consists of 4 symmetric pairs of coils to the equatorial plane. Each coil is wound with no internal joints by the continuous pancake winding method. It operates with pulsing current, which naturally induces inductive voltages across coils. Minimizing the inductive voltages is critical for the quench detection. To suppress the inductive voltages, each coil voltage was measured by using conductive tapes that are wound at the outer surface of the jacket with the same pitch length of the final sub-cable. During the KSTAR campaigns, the voltages were collected and analyzed. In addition, more rejection schemes were applied to enhance the stability and reliability of the quench detection. The paper deals with the up-to-date quench detection method of the KSTAR CS magnet system and its experimental results.