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(TH/4-1) Blobs and Cross-Field Transport in the Tokamak Edge Plasmas

S.I. Krasheninnikov1), A.Yu. Pigarov1)6), S.A. Galkin1), G.Q. Yu1), D.A. D’Ippolito2), J.R. Myra2), D.R. McCarthy3), W.M. Nevins4), T.D. Rognlien4), X.Q. Xu4), J.A. Boedo1), D.L. Rudakov1), M.J. Schaffer5), W.P. West5), D.G. Whyte1)
1) University California San Diego, La Jolla, USA
2) Lodestar Research Corporation, Boulder, Colorado, USA
3) Southeastern Louisiana University, Hammond, Louisiana, USA
4) Lawrence Livermore National Laboratory, Livermore, California, USA
5) General Atomics, San Diego California, USA
6) Kurchatov Institute of Atomic Energy, Moscow, Russia

Abstract.  Recent analysis of experimental data from different tokamaks suggests rather fast radial plasma transport in the scrape of layer (SOL) having convective rather than diffusive character. One of the possible mechanisms of fast convective plasma transport in the SOL can be associated with plasma blobs: coherent structures extended along the magnetic field lines with density much higher than the ambient plasma density in the far SOL. The origin of these blobs in the SOL can be plasma turbulence in the separatrix region. We present the results of our studies of different aspects of fast non-diffusive plasma transport in the SOL: a) simplified analytic theory of individual blob propagation, b) 2D and 3D modeling of the blobs with turbulence codes, and c) macroscopic transport modeling of the edge plasma transport in tokamaks. We show that our analytic estimate of the blob velocity and flux and density profiles being supported by our 2D and 3D modeling of the edge plasma turbulence are in a good agreement with recent experimental data. The results of our modeling of the DIII-D macroscopic edge plasma transport confirm the crucial importance of convective transport for the edge plasma.

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IAEA 2003