(TH/P8-40) Core and Edge Full-f ITG Turbulence with Self-consistent Neoclassical and Mean Flow Dynamics Using a Real Geometry Particle Code XGC1

S. Ku1), C.S. Chang1), M. Adams2), E. D'Azevedo3), Y. Chen4), P. Diamond5), L. Greengard1), T.S. Hahm6), Z. Lin7), S. Parker4), H. Weitzner1), P. Worley3), D. Zorin1)
1) New York University, New York, U.S.A.
2) Columbia University, New York, U.S.A.
3) Oak Ridge National Laboratory, U.S.A.
4) University of Colorado, Boulder, U.S.A.
5) University of California, San Diego, U.S.A.
6) Princeton Plasma Physics laboratory, U.S.A.
7) University of California, Irvine, U.S.A.

Abstract.  We report new core and edge physics of the ITG turbulence including the turbulence-driven mean and neoclassical background dynamics self-consistently, using a full-f gyrokinetic code XGC1 in a real tokamak geometry with magnetic X-point and conserving nonlinear Fokker-Planck Coulomb collisions. Some of the new findings in the core plasma are 1) the initial ITG modes growth is rather quasilinear than linear. Accordingly, highly anisotropic growth of streamers may not be observed experimentally. 2) Strong interaction of the ITG turbulence with the mean and neoclassical background dynamics results in an ion heat conductivity closer to the experimental observations (∼1 m2/s), even in the cyclone plasma, than the much higher values obtained from the conventional delta - f simulation. 3) Plasma temperature gradient is relaxed to marginally stable ηi and maintained throughout the nonlinear stage, thus exhibiting temperature profile stiffness. Some surprising new findings in the edge are 1) The ITG turbulence exists in a mild pedestal where the local ηi is lower than the conventionally known critical values from the core plasma profiles. 2) Stronger interaction of ITG with mean/neoclassical field in the pedestal does not allow any streamer-like structures in the growth stage. 3) There is a strong co-current parallel flow of the background plasma in the scrape-off region, which is stronger at the high field side. 4) At the same time, there is a mean E×B rotation in the positive poloidal direction (carrying the plasma toward the inner divertor) near the separatrix. E×B rotation is in the negative poloidal direction near the wall due to the wall-sheath effect. Thus, a large convective E×B circulation of the plasma is formed in the scrape-off layer, during which many particles hit the divertor plate. Other important issues to be presented include radial momentum pinch and diffusion, internal transport barrier formation in a central reverse sheared magnetic geometry, L-H transition study, role of zonal and mean flow to the nonlinear saturation, the role of neoclassical field on turbulence, neutral effect on the edge turbulence, and experimental validation.

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