Validation of TGLF-EP+Alpha model of Alfv\'en Eigenmode induced transport with the Imaging FIDA diagnostic on DIII-D

A reduced critical-gradient model for transport of energetic particles (EPs) by Alfv\'en Eigenmodes (AEs), constituted by the combination of TGLF-EP and Alpha codes, is tested against DIII-D L-mode discharges, where the EP population is measured with a new high resolution Imaging Fast Ion D-Alpha (I-FIDA) diagnostic. The outstanding spatial resolution of the I-FIDA diagnostic enables detailed comparisons to the transported EP profile and critical gradient threshold predicted by the model. The I-FIDA system measures a portion of the fast-ion population, generating 2D images with $\leq$2 mm resolution of the co-passing EPs in the energy range E$\simeq$40-80 keV with integration time $\geq 5$ ms. A beam modulation technique is employed to extract the active part of the FIDA signal, limiting the profile measurement rate to $\leq 50$ Hz. To compare measurements to the model, the EP diffusion coefficient profile computed by TGLF-EP+Alpha is input to the TRANSP (NUBEAM) code to compute the fast-ion distribution, which is processed by the FIDASIM code to generate synthetic diagnostic signal. Trends in the critical gradient threshold predicted by the model will be tested experimentally in L-mode discharges for a range of parameters, including magnetic shear and EP profiles and fraction.