Transport barrier onset and edge turbulence shortfall in fusion plasmas

Guilhem Dif-Pradalier (1) , Philippe Ghendrih (1) , Yanick Sarazin (1) , Elisabetta Caschera (1) , Frédéric Clairet (1) , Yann Camenen (2) , Peter Donnel (1) , Xavier Garbet (1) , Virginie Grandgirard (1) , Yann Munschy (1) , Laure Vermare (3) , Fabien Widmer

1 IRFM - Institut de Recherche sur la Fusion par confinement Magnétique
2 PIIM - Physique des interactions ioniques et moléculaires
3 LPP - Laboratoire de Physique des Plasmas

Magnetic confinement fusion offers the promise of sustainable and safe energy production on Earth. Advanced experimental scenarios exploit the fascinating yet uncommon ability of confined plasmas to bifurcate into states of enhanced performance upon application of additional free energy sources. Self-regulation of small-scale turbulent eddies is essential to accessing these improved regimes. However, after several decades, basic principles for these bifurcations are still largely debated and clarifications from first principles lacking. We show here, computed from the primitive kinetic equations, establishment of a state of improved confinement through self-organisation of plasma microturbulence. Our results highlight the critical role of the interface between plasma and material boundaries and demonstrate the importance of propagation of turbulence activity beyond regions of convective drive. These observations strongly suggest a paradigm shift where the magnetised plasma at the onset of enhanced performance self-organises into a globally critical state, ‘nonlocally’ controlled by fluxes of turbulence activity.

Domaines: Physique des plasmas [physics.plasm-ph]

Guilhem Dif-Pradalier, Philippe Ghendrih, Yanick Sarazin, Elisabetta Caschera, Frédéric Clairet, et al.. Transport barrier onset and edge turbulence shortfall in fusion plasmas. Communications Physics, 2022, 5 (1), pp.229. ⟨10.1038/s42005-022-01004-z⟩. ⟨hal-03845402⟩