A fast code using nonmagnetic measurements for RFX current and magnetic field profile reconstruction

Fast identification techniques of the plasma internal magnetic structure are needed for the real time control of the plasma current distribution in magnetic confinement devices. In this paper, a fast identification code using plasma internal nonmagnetic measurements is proposed and applied to the reversed field pinch experiment. The identification tool is based on a force-free ideal magnetohydrodynamic equilibrium model, using a parametric radial profile for the magnetic field and current density. A set of constraints on the internal magnetic distribution are derived from the Faraday rotation data given by a five-chord polarimeter, assuming the plasma density as given by an interferometric diagnostic. The code execution time is about a few seconds.