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(TH/P3-07) Simulations of Boundary Turbulence in Tokamak Experiments

W. M. Nevins1), X.Q. Xu1), T.N. Carlstrom5), R.H. Cohen1), R. Groebner5), T. Jennings2), B. LaBombard2), R.A. Maqueda4), A. Mazurenko2), G.R. McKee8), R. Moyer7), D. Mossessian2), M. Porkolab2), G.D. Porter1), M.E. Rensink1), T.L. Rhodes6), T.D. Rognlien1), C. Rost2), J. Snipes2), D.P. Stotler3), J. Terry2), S. Zweben3)
1) Lawrence Livermore National Laboratory, Livermore, CA, USA
2) Massachusetts Institute of Technology, Cambridge, MA, USA
3) Princeton Plasma Physics Laboratory, Princeton, NJ, USA
4) Los Alamos National Laboratory, Los Alamos, NM, USA
5) General Atomics, San Diego, CA, USA
6) University of California, Los Angeles, CA, USA
7) Univeristy of California, San Diego, CA USA
8) University of Wisconsin, Madison, WI, USA

Abstract.  Direct numerical simulations, which are easily diagnosed and have greater scope for parameter variations than experiments, provide a new means of studying the boundary turbulence observed in tokamaks. Simulations are most interesting insofar as they reproduce phenomena observed in magnetic confinement devices. We present comparisons between the boundary plasma turbulence observed in the BOUT code and experiments on C-Mod, NSTX, and DIII-D. BOUT is a 3D non-local electromagnetic turbulence simulation code which models boundary-plasma turbulence in a realistic divertor geometry using the modified Braginskii equations for plasma vorticity, density, the electron and ion temperatures and parallel momenta. Many features of the Quasi-Coherent (QC) mode, observed at high densities during enhanced D-alpha H-Mode in Alcator C-Mod, are reproduced in BOUT simulations. The spatial structure of boundary plasma turbulence as observed by gas puff imaging (GPI) from discharges on NSTX and C-Mod are in general (NSTX) to good (C-Mod) agreement with BOUT simulations. Finally, simulations of DIII-D L-mode experiments near the H-mode threshold are in broad agreement with the experimental results.

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IAEA 2003