Simulation of H-mode Edge Turbulence and Comparison to Phase Contrast Imaging Measurements on DIII–D

Initial comparisons have been made between H-mode edge turbulence observed with Phase Contrast Imaging and simulations of the edge region with CGYRO. The PCI[1] diagnostic on DIII–D observes high-frequency ion-scale turbulence in Quiescent H-mode localized to the center of the E_r well, providing an absolutely calibrated, wavenumber-resolved measurement in a stationary plasma. Simulations using CGYRO[2], a gyrokinetic solver for collisional plasmas, find broadband turbulence to be unstable in the bottom of the E_r well, causing transport that matches the experimental particle and energy fluxes in both the electron and ion channels. Post processisng with a synthetic PCI diagnostic model shows the peak spectral amplitude approaches the experimental value, though the spectral width is much narrower. Study of these discrepancies and identification of the instability are ongoing, along with expanding the simulated region deeper into the pedestal.

[1] E.M. Davis at al, Rev. Sci. Instrum. 87 (2016) 11E117.

[2] J. Candy, E.A. Belli, and R.V. Bravenec, J. Comput. Phys. 324 (2016) 73.