Transport in fusion plasmas: is the tail wagging the dog?

Authors:
  • GDGuilhem Dif-Pradalier
    Guilhem Dif-Pradalier
  • PGPhilippe Ghendrih
    Philippe Ghendrih
  • YSYanick Sarazin
    Yanick Sarazin
  • YCYann Camenen
    Yann Camenen
  • PDPeter Donnel
    Peter Donnel
  • XGXavier Garbet
    Xavier Garbet
  • VGVirginie Grandgirard
    Virginie Grandgirard
  • YMYann Munschy
    Yann Munschy
  • LVLaure Vermare
    Laure Vermare
  • FWFabien Widmer
    Fabien Widmer
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Abstract
Turbulent plasmas notably self-organize to higher energy states upon application of additional free energy sources or modification of edge operating conditions. Mechanisms whereby such bifurcations occur have been actively debated for decades. Enhanced confinement occurs at the plasma edge, where a shortfall of predicted turbulence intensity has been puzzling scientists for decades. We show, from the primitive kinetic equations that both problems are connected and that interplay of confined plasma turbulence with its material boundaries is essential to curing the shortfall of predicted turbulence and to triggering spontaneous transport barrier onset at the plasma edge. Both problems determine access to improved confinement and are central to fusion research. A comprehensive discussion of the underlying mechanisms is proposed. These results, highly relevant to the quest for magnetic fusion may also be generic to many problems in fluids and plasmas where turbulence self-advection is active.