Quench Detection of the KSTAR CS Coil by Considering Plasma Current Effect

Abstract

The plasma-driven inductive voltages were not negligible and should be taken into account for the reliable operation of the voltage-based quench detection of the KSTAR CS coil. For the active compensation of such plasma-induced voltage noise, plasma parameters should be measured in real-time and applied to the quench detection system. The selection of plasma parameters by considering their contribution to the noise is of primary importance. A code, which can estimate the induced coil voltage driven by plasma, is developed by using a simplified plasma response modeling. The numerical analysis has showed that there is an apparent influence from the plasma, while the influence from eddy currents induced in passive structures is negligible. The change of plasma current is the primary noise source and the radial and vertical motions of plasma have an effect, although they are small. The performance of the quench detector is developed and tested during the 2017 KSTAR campaign. The noise rejection performance is discussed with various experimental results and numerical estimations.