Equilibrium analysis of JET tokamak discharges

Equilibrium analysis is one of the essential tools for determining the plasma shape and profiles, in particular the current density and safety factor, as well as global physical quantities. We report on recent developments of the equilibrium code EFIT, which is used for the routine analysis of JET tokamak discharges. A new method to treat the iron transformer surrounding the JET device is presented. This is one of the prerequisites for the development of a real-time discharge analysis and feedback of physical quantities. A new type of constraint derived from the shape of the ECE temperature profile has been implemented which allows for an enhanced precision of the position of the magnetic axis and the safety factor. (orig.)