1 OV / 5 - 2 Ra Overview of RFX - mod results

With the exploration of the MA plasma current regime in up to 0.5 s long discharges, RFX-mod has opened new and very promising perspectives for the Reversed Field Pinch (RFP) magnetic configuration, and has made a significant progress in understanding and improving confinement and in controlling plasma stability. A big leap with respect to previous knowledge and expectations on RFP physics and performance has been made by RFX-mod since the last 2006 IAEA Fusion Energy Conference. A new self-organised helical equilibrium has been found (the Single Helical Axis – SHAx – state), which is the preferred state at high current. This regime is characterized by strong core electron transport barriers, with electron temperature gradients comparable to those achieved in tokamaks, and by a factor four improvement in confinement time with respect to the standard RFP. RFX-mod is also providing leading edge results on real-time feedback control of MHD instabilities, of general interest for the fusion community. 1. RFX-mod: mission, results, and challenges RFX-mod [1] is the largest reversed field pinch (RFP) device and it is capable of achieving the highest plasma current. It is based in Padova, Italy and its major and minor radii are R=2 m and a=0.459 m respectively, for a plasma volume of about 10 m. The maximum design plasma current is 2 MA, which allows exploring current regimes comparable to those of large tokamaks, but with a toroidal magnetic field ten times smaller. RFX-mod is the renewed and upgraded version of the former RFX device, and started its operation in December 2004. The original RFX thick shell (which had a magnetic field