Internal and edge electron transport barriers in the RFX-mod Reversed Field Pinch

IAEA Fusion Energy Conference 2010 Proceedings of the 23rd IAEA Fusion Energy Conference Daejeon, 11-16 October 2010 Organized by the International Atomic Energy Agency and hosted by the Government of the Republic of Korea IAEA-CN-180 (EXC/P4-10) Internal and Edge Electron Transport Barriers in the RFX-Mod Reversed Field Pinch M.E. Puiatti1), M. Valisa1), A. Alfier1), M. Agostini1), L. Apolloni1), F. Auriemma1), M. Baruzzo1), T. Bolzonella1), D. Bonfiglio1), F. Bonomo1), A. Canton1), S. Cappello1), L. Carraro1), R. Cavazzana1), S. Dal Bello1), G. De Masi1), D.F. Escande2), A. Fassina1), P. Franz1), E. Gazza1), M. Gobbin1), S. Guo1), P. Innocente1), R. Lorenzini1), G. Marchiori1), L. Marrelli1), P. Martin1), E. Martines1), S. Martini1), S. Menmuir1), B. Momo1), L. Novello1), R. Paccagnella1), P. Piovesan1), L. Piron1), I. Predebon1), A. Ruzzon1), F. Sattin1), A. Scaggion1), P. Scarin1), A. Soppelsa1), G. Spizzo1), S. Spagnolo1), M. Spolaore1), D. Terranova1), M. Veranda1), N. Vianello1), P. Zanca1), B. Zaniol1), L. Zanotto1), M. Zuin1) 1) Consorzio RFX, Associazione EURATOM-ENEA sulla Fusione, Padova, Italy 2) Laboratoire PIIM, UMR 6633 CNRS-Aix Marseille Université, France Abstract. An interesting result of the self-organization processes in RFX-mod high current discharges is the development of strong electron transport barriers. An internal heat and particle transport barrier is formed when a bifurcation process changes the magnetic configuration into a helical equilibrium (SH) and chaos reduction follows, together with the formation of a null in the q shear. Turbulence analysis shows that the large electron temperature gradients are likely limited by the onset of micro-tearing modes. A new type of electron transport barrier with strong temperature gradients develops more externally (r/a = 0.8), independently on the presence of the helical equilibrium, accompanied by a 30% improvement of the global confinement time. Both types of barriers occur in high current low collisionality regimes. Analogies with Tokamak and Stellarators are discussed.