Demonstration of H-mode Error Field Identification in a Single Discharge via Island Healing
Non-disruptive compass scan error field identification via island healing is demonstrated on KSTAR in a single H-mode discharge. This method can allow for up to a 75% reduction in the operational time necessary for a complete compass scan by reducing the required discharges from four to one. Previous experiments on DIII-D, JET, and MAST-U have demonstrated the technique in Ohmic and L-mode but required multiple discharges and strong real-time n=1 magnetics diagnostics close to the plasma that are unlikely to be viable for future devices. The results presented here were made possible by implementing a new set of triggering algorithms relevant to fusion pilot plant operation into the KSTAR plasma control system, along with KSTAR's strong RMPs and long pulse lengths. This represents a significant step towards the disruption-free error field identification method being demonstrated for deployment on future disruption-averse tokamaks, including ITER and fusion pilot plants. Steps needed to close remaining gaps to viability are addressed.