APP-FPP: Advanced Profile Prediction for Fusion Pilot Plants – a new DOE FIRE Collaboratory

The APP-FPP FIRE Collaboratory will close key gaps in designing economically attractive fusion power plants, namely the ability to reliably predict the performance of future tokamaks and stellarators. APP-FPP is developing the first accelerated gyrokinetic whole-device simulations, including from the pedestal top to divertor, featuring accurate yet practical gyrokinetic predictions for edge and divertor profiles with integrated kinetic neutrals and wall response, including impurity sputtering and transport. A recent 500x speedup of gyrokinetic edge turbulence simulations in realistic magnetic geometry including X-points, combined with hybrid solvers using machine learning to accelerate core gyrokinetic profile predictions and consistent calculations of plasma-materials interactions, bring gyrokinetic whole device profile prediction within reach. This new capability will be used to address power exhaust and core/edge integration challenges by providing reliable edge physics extrapolations for future ELM-free operating regimes, where pedestal pressures are limited by turbulent transport rather than macrosopic stability. The integrated simulations will predict the impact of tungsten walls in tokamaks, and will predict stellarator profiles from axis to wall. The project focuses on key issues for next-generation facilities with input from an Advisory Board guided by private companies and ITER R&D leadership.