Virtual Rogowskii loops for the evaluation of plasma and in-vessel eddy currents in the KSTAR tokamak

A simple but effective method is proposed for the estimation of plasma and in-vessel eddy currents in the KSTAR device. It is based on the prescribed contour integrals of the tangential magnetic fields measured by magnetic probes. It is shown that the method can estimate the plasma current in 0.33% accuracy. It is also found that the total in-vessel eddy current can be determined with accuracy within a few kiloamperes regardless of plasma conditions.