Articolo in rivista, 2022, ENG, 10.1038/s41567-022-01626-8

Enhanced performance in fusion plasmas through turbulence suppression by megaelectronvolt ions

Mazzi S.; Garcia J.; Zarzoso D.; Kazakov Ye.O.; Ongena J.; Dreval M.; Nocente M.; Stancar Z.; Szepesi G.; Eriksson J.; Sahlberg A.; Benkadda S.

Aix-Marseille University, CNRS, PIIM, Marseille, France; IRFM, CEA, Saint Paul Lez Durance, France; Laboratory for Plasma Physics, LPP-ERM/KMS, TEC Partner, Brussels, Belgium; Institute of Plasma Physics, National Science Center, Institute of Physics and Technology, Kharkiv, Ukraine; V.N. Karazin Kharkiv National University, Kharkiv, Ukraine; University of Milano-Bicocca, Milan, Italy; CNR ISTP - Institute for Plasma Science and Technology, Milan, Italy; Slovenian Fusion Association (SFA), Jozef Stefan Institute, Ljubljana, Slovenia; Culham Science Centre, UK Atomic Energy Authority, Abingdon, UK; Department of Physics and Astronomy, Uppsala University, Sweden.

Alpha particles with energies on the order of megaelectronvolts will be the main source of plasma heating in future magnetic confinement fusion reactors. Instead of heating fuel ions, most of the energy of alpha particles is transferred to electrons in the plasma. Furthermore, alpha particles can also excite Alfvénic instabilities, which were previously considered to be detrimental to the performance of the fusion device. Here we report improved thermal ion confinement in the presence of megaelectronvolts ions and strong fast ion-driven Alfvénic instabilities in recent experiments on the Joint European Torus. Detailed transport analysis of these experiments reveals turbulence suppression through a complex multi-scale mechanism that generates large-scale zonal flows. This holds promise for more economical operation of fusion reactors with dominant alpha particle heating and ultimately cheaper fusion electricity.

Nature physics (Online) 18 , pp. 776–782

Keywords

fusion plasmas, turbulence suppression, megaelectronvolt ions

CNR authors

Nocente Massimo

CNR institutes

ISTP – Istituto per la Scienza e Tecnologia dei Plasmi