Radiative Impurity Impact on 2D Inter-ELM Pedestal Fluctuation Measurements on DIII-D

Localized 2D measurements of low-to-intermediate wavenumber density fluctuations in the H-mode pedestal reveal a range of broadband modes that vary temporally and spatially during the inter-ELM cycle. Neon injected to radiate power significantly increases turbulence in the range of 50-300 kHz near ρ = 0.95, demonstrating a strong Z_eff and/or collisionality dependence.  These measurements are obtained with Beam Emission Spectroscopy and a new higher radial resolution (ΔR ~ 0.4cm) multichannel Charge eXchange Imaging (CXI) prototype diagnostic. Fluctuation characteristics will be presented as a function of collisionality and impurity density, which have been predicted to impact the growth rate of microtearing modes (MTM) and other pedestal-localized instabilities. A future optimized CXI diagnostic will measure carbon density fluctuations across the pedestal with higher sensitivity and complement the Beam Emission Spectroscopy (BES) system, which is limited to about 1 cm radial resolution. Simulated pySTRAHL and pyFIDASIM results confirm the enhanced spatial resolution of CXI and are being used to understand the origin and magnitude of electron impact and neutral charge exchange emission.