Observations and Empirical Scalings of the High-Confinement Mode Pedestal on Alcator C-Mod

and disposal, in whole or in part, by or for the United States government is permitted. Observations and empirical scalings of the high-confinement mode pedestal on Alcator C-Mod J.W. Hughes, D.A. Mossessian, A.E. Hubbard, B. LaBombard, E.S. Marmar On the Alcator C-Mod tokamak [Phys. Plasmas 1, 1511, (1994)], radial pro-files of electron temperature (Te) and density (ne) are measured at the plasma edge with millimeter resolution Thomson scattering [Rev. Sci. Instrum. 72, 1107 (2001)]. Edge transport barriers in the high confinement regime (H-mode) exhibit Te, ne pedestals with typical widths of 2–6 mm, with the Te pedestal on average slightly wider than and inside the ne pedestal. Measure-ments at both the top and the base of the pedestal are consistent with profiles obtained using other diagnostics. The two primary H-mode regimes on C-Mod, enhanced Dα (EDA) and edge-localized mode free (ELM-free), have been ex-amined for differences in pedestals. EDA operation is favored by high edge collisionality ν, in addition to high edge safety factor q95. Scaling studies at fixed shape yield little systematic variation of pedestal widths with plasma parameters, though higher triangularity is seen to increase the ne pedestal width dramatically. Pedestal heights and gradients show the clearest depen-dencies on plasma control parameters. Pedestal ne and Te both scale linearly with plasma current IP, while pedestal Te depends strongly on power flowing from the core plasma into the scrape-off layer PSOL. The electron pressure (pe) pedestal and pe gradient both scale with I 2 P