Evolution of Edge Pedestal Profiles Over the L-H Transition

The detailed time evolution of thermal diffusivities, electromagnetic forces, pressure gradients, particle pinch and momentum transport frequencies (which determine the diffusion coefficient) have been analyzed during the L-H transition in a DIII-D discharge. Density, temperature, rotation velocity and electric field profiles at times just before and after the L-H transition are analyzed in terms of these quantities. The analysis is based on the fluid particle balance, energy balance, force balance and heat conduction equations, as in Ref.~[1], but with much greater time resolution and with account for thermal ion orbit loss. The variation of diffusive and non-diffusive transport over the L-H transition is determined from the variation in the radial force balance (radial electric field, $V\times B$ force, and pressure gradient) and the variation in the interpreted diffusive transport coefficients.\par \vskip6pt \noindent [1] W.M.\ Stacey and R.J.\ Groebner, Phys.\ Plasmas {\bf 17}, 112512 (2010).