Abstract

In the quest for new energy sources, the research on controlled thermonuclear fusion1 has been boosted by the start of the construction phase of the International Thermonuclear Experimental Reactor2 (ITER). ITER is based on the tokamak magnetic configuration3, which is the best performing one in terms of energy confinement. Alternative concepts are however actively researched, which in the long term could be considered for a second generation of reactors. Here, we show results concerning one of these configurations, the reversed-field pinch4,5 (RFP). By increasing the plasma current, a spontaneous transition to a helical equilibrium occurs, with a change of magnetic topology. Partially conserved magnetic flux surfaces emerge within residual magnetic chaos, resulting in the onset of a transport barrier. This is a structural change and sheds new light on the potential of the RFP as the basis for a low-magnetic-field ohmic fusion reactor.

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Acknowledgements

We thank the whole Consorzio RFX staff for the support in the device operation. This work has been supported by the European Communities under the contract of Association between EURATOM and ENEA.

Author information

Affiliations

  1. Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova 35137, Italy

    • R. Lorenzini
    • , E. Martines
    • , P. Piovesan
    • , D. Terranova
    • , P. Zanca
    • , M. Zuin
    • , A. Alfier
    • , D. Bonfiglio
    • , F. Bonomo
    • , A. Canton
    • , S. Cappello
    • , L. Carraro
    • , R. Cavazzana
    • , A. Fassina
    • , P. Franz
    • , M. Gobbin
    • , P. Innocente
    • , L. Marrelli
    • , R. Pasqualotto
    • , M. E. Puiatti
    • , M. Spolaore
    • , M. Valisa
    • , N. Vianello
    •  & P. Martin
  2. Physique des Interactions Ioniques et Moléculaires, UMR 6633—CNRS/Aix Marseille Université, France

    • D. F. Escande
  3. Dipartimento di Fisica ‘G. Galilei’, Università di Padova, Padova 35131, Italy

    • A. Fassina
    •  & P. Martin
  4. Consorzio RFX, Associazione EURATOM-ENEA sulla Fusione, 35137 Padova, Italy

    • P. Martin
    • , L. Apolloni
    • , M. E. Puiatti
    • , M. Agostini
    • , A. Alfier
    • , V. Antoni
    • , F. Auriemma
    • , O. Barana
    • , M. Baruzzo
    • , P. Bettini
    • , T. Bolzonella
    • , D. Bonfiglio
    • , F. Bonomo
    • , M. Brombin
    • , A. Buffa
    • , A. Canton
    • , S. Cappello
    • , L. Carraro
    • , R. Cavazzana
    • , M. Cavinato
    • , G. Chitarin
    • , S. Dal Bello
    • , A. De Lorenzi
    • , G. De Masi
    • , D. F. Escande
    • , A. Fassina
    • , A. Ferro
    • , P. Franz
    • , E. Gaio
    • , E. Gazza
    • , L. Giudicotti
    • , F. Gnesotto
    • , M. Gobbin
    • , L. Grando
    • , L. Guazzotto
    • , S. C. Guo
    • , P. Innocente
    • , R. Lorenzini
    • , A. Luchetta
    • , G. Manduchi
    • , G. Marchiori
    • , D. Marcuzzi
    • , L. Marrelli
    • , S. Martini
    • , E. Martines
    • , F. Milani
    • , M. Moresco
    • , L. Novello
    • , S. Ortolani
    • , R. Paccagnella
    • , R. Pasqualotto
    • , S. Peruzzo
    • , R. Piovan
    • , P. Piovesan
    • , L. Piron
    • , A. Pizzimenti
    • , N. Pomaro
    • , I. Predebon
    • , G. Rostagni
    • , F. Sattin
    • , P. Scarin
    • , G. Serianni
    • , P. Sonato
    • , E. Spada
    • , A. Soppelsa
    • , S. Spagnolo
    • , M. Spolaore
    • , G. Spizzo
    • , C. Taliercio
    • , D. Terranova
    • , V. Toigo
    • , M. Valisa
    • , N. Vianello
    • , P. Zaccaria
    • , A. Zamengo
    • , P. Zanca
    • , B. Zaniol
    • , L. Zanotto
    • , E. Zilli
    •  & M. Zuin
  5. Institute of Plasma Physics, Association EURATOM-IPP.CR, Prague 18200, Czech Republic

    • J. Adamek
    •  & J. Brotankova
  6. Space and Plasma Physics, EE KTH, SE-10044 Stockholm, Sweden

    • S. V. Annibaldi
    •  & P. Buratti
  7. Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA

    • B. E. Chapman
    • , K. McCollam
    • , J. A. Reusch
    •  & J. S. Sarff
  8. UMR 6633 CNRS-Université de Provence, Marseille, France

    • D. F. Escande
  9. Max-Planck-Institut für Plasmaphysik, EURATOM Association, 85748 Garching, Germany

    • V. Igochine
    • , D. Yadikin
    •  & H. Zohm
  10. EURATOM-UKAEA Fusion Ass., Culham Science Centre, Abingdon OX14 3DB, UK

    • Y. Q. Liu
  11. Ass. Euratom/ENEA/CREATE, DIEL, Università di Napoli Federico II, Napoli 80125, Italy

    • G. Rubinacci
  12. Ass. Euratom/ENEA/CREATE, DAEIMI, Università di Cassino, Cassino 03043, Italy

    • F. Villone
  13. Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA

    • R. B. White

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Contributions

The experiments were carried out by the whole RFX team, R.L., E.M., P.P., D.T., P.Z., M.Z. jointly conceived this paper, in close collaboration with A.A., D.B., F.B., A.C., S.C., L.C., R.C., D.F.E., A.F., P.F., M.G., P.I., L.M., R.P., M.S., M.V. and N.V. and with M.E.P. and P.M. who lead the RFX science programme.

P. Martin5, L. Apolloni5, M. E. Puiatti5, J. Adamek6, M. Agostini5, A. Alfier5, S. V. Annibaldi7, V. Antoni5, F. Auriemma5, O. Barana5, M. Baruzzo5, P. Bettini5, T. Bolzonella5, D. Bonfiglio5, F. Bonomo5, M. Brombin5, J. Brotankova6, A. Buffa5, P. Buratti7, A. Canton5, S. Cappello5, L. Carraro5, R. Cavazzana5, M. Cavinato5, B. E. Chapman8, G. Chitarin5, S. Dal Bello5, A. De Lorenzi5, G. De Masi5, D. F. Escande5,9, A. Fassina5, A. Ferro5, P. Franz5, E. Gaio5, E. Gazza5, L. Giudicotti5, F. Gnesotto5, M. Gobbin5, L. Grando5, L. Guazzotto5, S. C. Guo5, V. Igochine10, P. Innocente5, Y. Q. Liu11, R. Lorenzini5, A. Luchetta5, G. Manduchi5, G. Marchiori5, D. Marcuzzi5, L. Marrelli5, S. Martini5, E. Martines5, K. McCollam8, F. Milani5, M. Moresco5, L. Novello5, S. Ortolani5, R. Paccagnella5, R. Pasqualotto5, S. Peruzzo5, R. Piovan5, P. Piovesan5, L. Piron5, A. Pizzimenti5, N. Pomaro5, I. Predebon5, J. A. Reusch8, G. Rostagni5, G. Rubinacci12, J. S. Sarff8, F. Sattin5, P. Scarin5, G. Serianni5, P. Sonato5, E. Spada5, A. Soppelsa5, S. Spagnolo5, M. Spolaore5, G. Spizzo5, C. Taliercio5, D. Terranova5, V. Toigo5, M. Valisa5, N. Vianello5, F. Villone13, R. B. White14, D. Yadikin10, P. Zaccaria5, A. Zamengo5, P. Zanca5, B. Zaniol5, L. Zanotto5, E. Zilli5, H. Zohm10 and M. Zuin5

Corresponding author

Correspondence to R. Lorenzini.

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DOI

https://doi.org/10.1038/nphys1308

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