Constructing a Correlation ECE Synthetic Diagnostic forGyrokinetic Simulations with Application to HSX

Transport driven by nonlinear, turbulent interactions of ion and electron scale fluctuations play a

critical role in determining the performance of stellarators and has not been directly addressed

in turbulence optimization. As numerical modeling and simulations are the primary method by

which turbulence optimization will be advanced, it is critical the underlying physics models be

validated through rigorous comparison of numerical simulations with experimental data.

To perform microturbulence validation, density-gradient-driven trapped electron mode (TEM)

microturbulence is studied in the HSX stellarator. Using the GENE code, nonlinear flux-tube

simulations of TEM microturbulence have been performed at experimentally relevant

parameters for HSX. A synthetic correlation ECE diagnostic has been constructed using the

spatial and temporal resolutions of the experimental diagnostic. The simulation data is mapped

from the co-rotating plasma frame to the laboratory frame and integrated over Gaussian point

spread functions centered on the diagnostic channels. These results, coupled with an

understanding of the errors in synthetic diagnostic implementation, e.g. introduced through

numerical Monte Carlo integration, provide an important basis on which a thorough validation

study will be based.