fusion Theory & Computation

Confinement and Transport

TORIC Full wave RF mode conversion

Confinement and transport investigations at the PSFC include fundamental theory and gyrokinetic simulation of turbulence, including trapped electron modes and neoclassical polarization, and simulations of turbulence for Alcator C-Mod and other tokamaks, emphasizing particle and momentum transport and toroidal rotation without explicit momentum input. 

Through gyrokinetic turbulence simulations and neoclassical calculations, we have developed a coherent and quantitative model of the transport processes underlying internal transport barrier (ITB) formation and control in C-Mod. The absence of core fueling in C-Mod provides the opportunity for a unique and fundamental study of particle transport in ITBs. In addition, we have been critically re-examining and improving formulations of many results of kinetic theory in order to better understand how to model turbulence and transport in tokamaks in the core and edge.

Examples of recent accomplishments:

• Important new insights into internal transport barrier operation in
  Alcator C-Mod
• Discovery of zonal flow upshift in trapped electron mode critical density gradient
• First self-consistent description of short mean free path transport for the drift ordering
• Removal of limitations of standard drift kinetics for treating viscous effects
• Evaluated Pfirsch-Schluter radial electric field for arbitrary cross-section tokamaks

Representative current research topics:

• Momentum pinches, electron temperature gradient streamers, and C-Mod fluctuations
• Sensitivity to magnetic topology of tokamak plasma flows
• Hybrid fluid-kinetic closure for arbitrary collisionality