Improvement of RFX performances by field and impurity control

The Reverse Field Pinch experiment RFX has been operated since 1992 with the principal objective of extending the knowledge of RFP confinement to larger dimensions and higher plasma currents. Experiments have been run between 500 and 900 kA; confinement parameters are mainly determined by magnetic field quality and plasma density behaviour. Significant improvements were obtained by feedback controlling the poloidal field configuration and by reducing the impurities produced by plasma-wall interactions.