Connecting DIII-D and NERSC to support DIII-D Operations through Kinetic Equilibrium Analysis

The CAKE (Consistent Automatic Kinetic Equilibrium) OMFIT workflow to reconstruct magnetic equilibria in the DIII-D tokamak with kinetic constraints has been automated to run in the NERSC realtime queue, connected to DIII-D via the ESnet network. These reconstructions had been carried out on the DIII-D local cluster, Iris, but took too long to make an impact on control room decisions. Optimizing the time to solution on NERSC’s Cori system (launched via the NERSC Superfacility API), with its greater parallelization possibilities, resulted in a run time for less well-converged cases of 22 minutes. Further improvements in runtime are anticipated in moving the workflow to Perlmutter at NERSC and improving the method for finding the optimal EFIT internal spline knot locations, including more parallelization. The solutions are written back into DIII-D’s MDSplus data management system and are then available to the entire DIII-D team, including visualization through the omas library.