Progress in coupling T3D transport solver with gyro-kinetic GX model with TRANSP

We report the successful integration of the T3D transport solver with the GX gyrokinetic (GK) solver into the TRANSP code. Accurate integrated plasma simulation is crucial for applications like experiment interpretation, physics validation, scenario discovery, and optimization. Integrated tokamak modeling requires consistent simulations of neoclassical and anomalous transport, equilibrium, and sources. High-fidelity models, though slower, provide essential accuracy for predicting future fusion reactor performance. Integrating GK computations into TRANSP via T3D enhances predictive capabilities. While T3D's numerical approach is similar to PT_SOLVER, the TRANSP predictive solver, T3D includes embedded turbulence with GK codes like GX, which are currently unavailable in TRANSP. The coupling of TRANSP with the T3D/GX model offers high-fidelity simulations needed for accurate tokamak research and Fusion Power Plant (FPP) predictions. Our work demonstrates the feasibility and stability of this coupling scheme using a file-based method for integrating TRANSP and T3D. By leveraging MPI and GPU-parallelized models for sources in TRANSP and the GPU-ready GX model in T3D, we created time-efficient coupled simulations on Traverse at PPPL and Perlmutter at NERSC. Results are presented for selected discharges from NSTX-U and JET.