 |
 |
 |
Institute for Plasma Research, University of Maryland, College
Park, MD 20742, USA
Max-Planck-Institut für Plasmaphysik, EURATOM Association,
85748 Garching, Germany
Abstract. Based on three-dimensional simulations of the Braginskii equations,
we identify two main parameters which control transport in the edge of
tokamaks: the MHD ballooning parameter and a diamagnetic parameter. The space
defined by these parameters delineates regions where typical L-mode levels of
transport arise, where the transport is catastrophically large (density limit)
and where the plasma spontaneously forms a transport barrier (H-mode). Ion
diamagnetic effects allow the edge pedestal to steepen well beyond the first
ideal MHD stability boundary.
IAEA 2001
