Analysis of Temperature and Density Pedestal in a Multi-Machine Database

A comparison of the AUG and DIII-D temperature pedestal showed significant differences between electrons and ions depending on collisionality. At high ne* the ions are coupled to the electrons and show very similar pedestal top values and gradients. For low ne* both decouple and the ion pedestal becomes less steep. The electron temperature gradient scales linearly with its pedestal top value. This trend is independent of collisionality and plasma shape. The normalized total pres- sure gradient shows strong correlations with the plasma shape, namely plasma elongation, and the collisionality in a way expected by peeling-ballooning theory. The different collisionality dependence of Te and p suggests a limit for the electron temperature pedestal different from linear edge MHD stability.
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