Near SOL profiles in DIII-D H-mode plasmas

Near SOL plasma profiles (≤ 1cm outside the midplane separatrix) in DIII-D H-mode are found to be narrower than expectations from parallel transport and ideal MHD stability models. The narrow SOL profiles are accurately resolved with the DIII-D high resolution edge Thomson scattering diagnostic. The midplane T_e profile is ~30% narrower than would be expected from dominant electron conductive heat transport for both the divertor measured heat flux profile and the heat flux width empirical scaling. Comparisons with modeling from UEDGE and BOUT++ suggest this can be attributed to plasma poloidal drifts dominating the energy transport into the divertor. While the narrow profiles broaden at high density conditions, the radial pressure gradient near the separatrix can exceed the ideal MHD ballooning limit by as much as a factor of two. Sensitivity to assumptions of separatrix location and the ion pressure contribution is also examined. Explanations for the excessive pressure gradient are explored with BOUT++ modeling including plasma flow shear and finite resistivity.  Reconciliation of the measured SOL profiles with the most sophisticated models increases confidence in using these tools to project boundary solutions in future devices.