Scaling of up–down asymmetric turbulent momentum flux with poloidal shaping mode number in tokamaks

Intrinsic momentum transport in up-down asymmetric tokamaks

Recent work demonstrated that breaking the up-down symmetry of tokamak flux surfaces removes a constraint that limits intrinsic momentum transport, and hence toroidal rotation, to be small. We show, through MHD analysis, that ellipticity is most effective at introducing up-down asymmetry throughout the plasma. We detail an extension to GS2, a local δf gyrokinetic code that self-consistently cal...

Toroidal Momentum Confinement in Tokamaks

Theories for the toroidal momentum confinement in tokamaks have been developed. It is shown that the logarithmic gradient of the toroidal flow is a linear combination of logarithmic gradients of the plasma pressure and the temperature in neoclassical quasilinear theory. The fluctuation-induced toroidal stress consists of a diffusion flux, a convective flux, and a residual flux. The effects of a...

Neoclassical calculation of poloidal rotation and poloidal density asymmetries in tokamaks

A previous model for the calculation of poloidal velocities and poloidal density asymmetries in the core of a tokamak plasma is refined and extended by the inclusion of terms which are important for the calculation of these quantities in the plasma edge. Agreement of predictions of the model with experiment is demonstrated. The effects of edge pressure gradient, collisionality, neutral density ...

Physics of Non-Diffusive Turbulent Transport of Momentum and the Origins of Spontaneous Rotation in Tokamaks

Recent results in the theory of turbulent momentum transport and the origins of intrinsic rotation are summarized. Special attention is focused on aspects of momentum transport critical to intrinsic rotation, namely the residual stress and the edge toroidal flow velocity pinch. Novel results include a systematic decomposition of the physical processes which drive intrinsic rotation, a calculati...

Up-down asymmetric tokamaks