Turbulence Broadening of Heat Flux Width in QH-Mode Plasmas and Future Relevance of Turbulence-Limited Pedestals

Future devices including SPARC, ITER, and FPP will operate at low ρ_* with reduced pedestal ExB shear suppression and high opacity, suggesting turbulence-limited pedestals like Wide Pedestal Quiescent H-Mode may naturally arise. Evidence for turbulence broadening of the divertor heat flux width in QH-Mode plasmas is presented. In the WPQH-Mode regime, measurements of the heat flux width λ_q =2.5-3.1 mm from divertor Langmuir probes are consistent with infra-red imaging and match the Eich scaling (2.7 mm). A torque increase forced a back-transition to Standard QH-Mode without coherent MHD, doubling turbulent density fluctuation levels in the pedestal and near SOL. Simultaneously, the measured heat flux width λ_q =5.2-5.3 mm from both diagnostics doubled relative to the unchanged Eich scaling value. Turbulence in the pedestal and near SOL was measured by Beam Emission Spectroscopy and Doppler Backscattering. Distinct ion- and electron-directed features are present in the BES spectrum. Their intensities are correlated with increased λ_q, while the stronger ion feature extends beyond the separatrix. Simulations using the XGC and BOUT++ codes are in progress. Finally, impurity injection reduced high WPQH-Mode SOL temperatures, reducing carbon sputtering to maintain high confinement with low carbon Z_eff.