Evaluating optimized stellarator performance via gyrokinetic-based profile predictions

Stellarator configurations that target reduced turbulent transport are now being routinely developed. This is accomplished using optimization approaches that rely on reduced models to capture key qualitative trends of the underlying drift wave stability and turbulence saturation. Here we use first-principles gyrokinetic simulations to evaluate the efficacy of these reduced models, and to quantitatively predict and evaluate the transport and energy confinement characteristics of the resulting configurations. Profile predictions are made with Trinity3D [t3d.readthedocs.io], which solves transport equations using fluxes computed from GX [Mandell, 2018; 2022] nonlinear gyrokinetic turbulence simulations. Profile predictions based on previously published configurations [Hegna, 2022] show trends consistent with the reduced models and standalone gyrokinetic analysis. However, the transport characteristics can vary in additional ways not incorporated within the optimization approach, pointing to opportunities for improvement. Similar predictions are being made for optimized configurations being developed by Type One Energy as part of its mission to develop a stellarator fusion pilot plant to address the White House Bold Decadal Vision for Commercial Fusion Energy.